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Synthesis, crystal structure and characterization of a new optical di-lithium di-phthalate single crystals
Accepted Manuscript Synthesis, crystal structure and characterization of a new optical di-lithium diphthalate single crystals D. Saravanan, G. Ramesh Kumar, S. Gokul Raj, S. Mohan, B. Sivakumar PII: DOI: Reference:
S1386-1425(15)00724-6 http://dx.doi.org/10.1016/j.saa.2015.06.010 SAA 13779
To appear in:
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Received Date: Revised Date: Accepted Date:
22 July 2014 3 June 2015 6 June 2015
Please cite this article as: D. Saravanan, G. Ramesh Kumar, S. Gokul Raj, S. Mohan, B. Sivakumar, Synthesis, crystal structure and characterization of a new optical di-lithium di-phthalate single crystals, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (2015), doi: http://dx.doi.org/10.1016/j.saa.2015.06.010
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1
Synthesis, Crystal structure and Characterization of a new optical Di-Lithium Di-phthalate single crystals
1
D. Saravanan1, G. Ramesh Kumar2, S. Gokul Raj3, S. Mohan3,*, B. Sivakumar4 Department of Physics, Sri Venkateshawaraa College of Engineering & Technology, Ariyur - 605102, India 2 Department of Physics, University College of Engineering Arni, Anna University Chennai, Arni -632317. India. 3 Department of Physics, Vel Tech University, Avadi, Chennai -600 062, India. 4 Department of Physics, University College of Engineering Kanchipuram, Anna University Chennai, Kanchipuram - 631552. India.
* Corresponding author: Prof. S. Mohan ([email protected])
Abstract: Single crystals of a new alkali phthalic complex salt of Di-lithium Di-phthalate (C32 H30 Li4 O21) (DLDP) were grown by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in a monoclinic system with a centrosymmetric space group having the unit cell parameters; a= 17.037(5) Å, b= 5.134(5) Å, and c=21.398(5) Å and α = 90.000(5) °, β = 113.195(5) °, and γ = 90.000(5) ° with Z= 2. The structure has been refined upto a R-value of 0.0828 from 26248 observed reflections using a three-dimensional X-ray diffraction intensity data. The vibrational structure of the compound confirms the presence of various functional groups in the molecule. Mass spectrometric analysis provides the molecular weight of the compound and possible ways of fragmentations occurring in the compound. Thermal stability of the crystal was also studied by simultaneous TGA/DTA analyses. The UV-VIS-NIR spectrum was recorded to study the transmittance properties of the grown crystals. The obtained results are discussed in detail.
Keywords: Di-Lithium Diphthalate ; Single crystal; Hydrogen bonds; FT-IR; UV-Vis-NIR; Mass spectrometry;
2 1. Introduction Synthesizing metallo-organic crystals have been reported as a new approach for materials with interesting nonlinear optical properties [1-4]. In metallo-organics, polarizable organic molecules are stoichiometrically bound with in an inorganic host [5]. The advantage of metallo-organic materials is that the crystal can be grown from aqueous solution and they form three-dimensional crystals which can be easily cut and polished [6]. The other favourable properties are high optical damage threshold, large thermal conductivity, adequate birefringence for phase matching and good mechanical characteristics.
The low-temperature solution growth is an important technique for
growing large-size nonlinear optical crystals. The crystals grown by this technique find wide spread applications in key areas like inertial confinement fusion [6], X-ray spectroscopy and laser energy measurement [7] etc., In order to grow large crystal, one has to ensure that the available nutrient is deposited on the chosen seed only during the growth period. Otherwise, any spontaneous nucleation occurring during the growth will take away a portion of the solute, thus making it difficult or impossible to grow a single large crystal. Although crystals of different orientations with different morphology are grown by conventional solution growth technique,
the specific orientation with good
quality is needed for applications. Several metallo-organic large-size good-quality single crystals such as Potassium acid phthalate (KAP), Sodium acid phthalate (NaAP) and Lithium acid Phthalate (LiAP) were successfully grown by this method [8-11]. Crystals of phthalic acid derivatives are potential candidates for NLO and electro-optic processes [12]. Rubidium acid phthalate (RbAP), Cesium acid phthalate (CsAP), Thallium acid phthalate(TiAP) and Ammonium acid phthalate(NH4AP) are well-known reported metallo-organic phthalic acid crystals. The inorganic hydrogen phthalate crystals are widely known for their applications in the long-wave X-ray spectrometers. Their optical, piezo-electric, NLO and elastic properties were already reported by Belyeav et al, [13]. In the present investigation, a new mixed Lithium Phthalate single crystal has been grown by the conventional slow cooling technique. The preliminary X-ray structure investigation revealed that the colourless crystals of Di-lithium Di-phthalate (DLDP) have unit cell parameters that differ from those of other Alkali acid phthalate crystals. Optical properties of acid phthalate crystals
3 were been reported in literature [9]. However, no study has been made so far on the new crystals of DLDP. Hence, the grown crystals of DLDP are subjected to various studies like single-crystal X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and Simultaneous TG and DTA analyses. UV-VIS-NIR absorption spectrum was also recorded for the title compound.
2. Experimental procedure 2.1. Crystal growth Di-lithium Di-phthalate was synthesized by the reaction between phthalic acid (EMerck 99.9%) and lithium Hydroxide (LOBO 99%) taken in an equimolar ratio 1:1. The reactants were thoroughly dissolved in double distilled water and stirred using a temperature controlled magnetic stirrer to get a homogeneous mixture of the solution. Then, the solution was allowed to evaporate at room temperature which yields crystalline salt of Di-lithium Diphthalate. The process of recrystallization was carried out to purify the synthesized salt. The reaction mechanism of DLDP is shown below.
Phthalic acid + Lithium hydroxide
Di-lithium Diphthalate
Scheme of reaction of DLDP
2.2 Characterization studies
4 The grown crystals of DLDP have been subjected to single crystal X-ray diffraction. The FTIR spectrum was recorded in the frequency range 400-4000cm-1 by employing Bruker IFS66 FTIR spectrometer using KBr pellet method. Mass spectral analysis was carried out using a JEOL GC mate mass spectrometer for confirming the formation of new title compound. Thermo gravimetric and differential thermal analyses were also carried out using NETSZCH STA 409C thermal analyzer. Optical absorption properties of the crystals were studied using a Varion Cary 5E UV-VIS-NIR spectrophotometer. The emission spectrum was recorded using JOBIN YVON Spectrofluorometer in wavelength range 200-400nm. 3. Results and discussion 3.1 Single crystal X-ray diffraction analysis The unit cell dimension and X-ray intensity data of DLDP was obtained on a Enraf Nonius CAD 4 Bruker Kappa APEX II single crystal X-ray diffractometer equipped with MoKα radiation (λ=0.71073 Å). ω/2θ scan mode was employed for data collection [14]. The dimension of the crystal used for the measurements was 0.30x0.20x0.20 mm3. A total of 26248 reflections were measured, out of which 7861 were found unique and its limiting indices were -23<=h<=28, -7<=k<=8, and 35<=l<=34. For the structure solution and refinement, the lattice parameters were refined for all the collected reflections. The estimated standard deviation (esd) was calculated using full variance-covariance matrix method for bond length and bond angle. Integrated intensities were reduced for Lorenz, polarization and decay corrections. Absorption corrections were employed based on
psi-scan mode [15]. The maximum and minimum
transmission factors were 0.95 and 0.90. The crystal structure was solved by direct method using SIR92 (WINGX)[16] and refinement was done by using SHELXL 97[17]. The hydrogen atoms of phthalic acid ring were located by difference Fourier map and was refined with isotropic thermal parameters. The crystallographic refinement parameters are listed in Table.1. The atomic coordinates and isotropic displacement parameters are listed in Table.2. The bond lengths and bond angles are listed in Table 3. Non-hydrogen atoms were refined with anisotropic displacement parameters whose values are provided in the Table.4. Other hydrogen atoms were fixed at meaningful
5 positions and were given riding model refinement. The refinement was continued until maximum shift was zero. The final refinement factor(R) was 0.0828. It was observed that the compound DLDP crystallizes in an Monoclinic crystal system with a centrosymmetric space group of P2/n. The unit cell parameters were found to be a = 17.037(5) Å; b = 5.134(5) Å and c = 21.398(5) Å .and α = 90.000(5) °; β = 113.195(5) °;γ = 90.000(5) ° and V= 1720.4 (18) Å3. Fig.1 shows the ORTEP (50% probability ellipsoid) representation of the molecule with numbering scheme. The unit cell pack up of DLDP is also shown in Fig 2. Hydrogen coordinates and isotropic displacement parameters are listed in the Table 5. The Torsion angles are listed in the Table 6. The various hydrogen bond parameters are listed in Table 7. From the ORTEP representation, it is perceived that the Li ions are coordinated by four O- atoms which form a slightly distorted tetrahedral fashion. The bond distances and bond angles of DLDP range from 1.839(2) Å- 2.008(2) Å and 99°-119° respectively. Li (1) is connected to the two oxygen of H2O molecules and the remaining two with the inner O atoms of the both carboxylic groups of the both phthalate ions, whereas Li (2) is connected to the oxygen and the remaining with the inner O atom of the carboxylic groups of one of the phthalic ions. Further, O (11) atoms are less ionized because they form an intramolecular hydrogen bond with O(4) atom bond distance of Li(1)-O was found to be longer and as the consequence the tetrahedron structure got more distorted. The
distance Li(1)-O(1), Li(1)-O(10), Li(1)-O(9), and Li(1)-O(6), are equal
within the tetrahedral bond distance of range 1.836(2) Å to 2.008(2) Å . O(10) and O(9) are involved in the hydrogen bonds with the water molecules. Hence, H(1) should be more closely attached to the O(4) than to O(2) because O(2) shows no interamolecular linkage. In a molecule of lowered symmetry with respect to linked neighbor, it is difficult to decide whether O(4) or O(3) is closer to the hydrogen. Bond distances and the corresponding angles in these tetrahedral connected Li atom of DLDP are given in the Table 8. The Li (1) ion occupies a position with an ionic contact between two phthalate ions and they are mutually interconnected by the strong ionic bonds between O (6) and Li
6 (1). Further, linkage is mainly achieved by a complicated frame work of seven O-H…O hydrogen bonds which are listed in Table.7. The water molecules are mutually interconnected by strong O-H..O hydrogen bonds forming infinite chains along the ‘ab’ direction. The tetrahedral co-ordination of Li 1 are linked along the ‘b’ direction by hydrogen bonds which are the connecting the edge of O(9)-H(9)-O(2) atoms with O(10) –H(10)-O(5) of the neighboring cell above and below the cell drawn in ORTEP via H(9) and H(10). The oxygen of three water molecules namely O(9), O(10) and O(11) are held in a rigid position by their contact with the Li ion through strong hydrogen bonds. Consequently, the positions of hydrated molecules can not be well defined due to the temperature factors. In case of Nickel diphthalate (NiDP) and Potassium diphthalate (KDIP) [18, 19], a regular octahedral network were observed wherein the bond distance of octahedraly positioned potassium ion with the oxygen atom vary from 2.805-2.986Å. All this metal organic complexes having a tetrahedral as well as octahedral metal ion occupies a special position with a site symmetry ī and hence the crystals are centric in nature. 3.2 Fourier transform infrared spectroscopy ( FTIR ) Fourier transform infrared (FTIR) spectrum of DLDP was recorded in the frequency range of 400 – 4000 cm-1 by KBr pellet method and is shown in Fig 3. A broad shoulder at 3428 cm-1 is due to OH stretching vibrations of the water molecule. A peak at 593 cm-1 is due to alkali metal stretching of the acid group. Similar vibrations also observed for KAP[20] . The aromatic ring is indicated by a peak at 1590 cm-1. The presence of carboxyl group can be identified from the appearance of bands at 1381, 428 and 548 cm-1 which correspond to symmetric stretching, rocking and wagging vibrations of COO- respectively. From X-ray data it was found that the entire molecule is stabilized by the three dimensional network of H-bonds and framed by seven O-H..O type strong hydrogen bonds. The broad shoulders around 3400, 1600 and 800 cm-1 are due to the fundamental vibrations and overtones of the hydrated molecules. The other vibrations for the phthalic acid group and that for the lithium with phthalate molecules are assigned in Table 9 which agree well with the reported values for other phthalate groups [21].
7 3.3 Mass spectrometry of DLDP Mass spectrometry was carried out for DLDP in the m/Z range 50 - 400 amu is shown in Fig.4. Since, the Phthalic acid molecule contains aromatic rings, a molecular ion peak could be observed at m/Z 77. The base peak at m/Z 104.24 corresponds to the C6H5CO+ ion and it clearly shows that the preferential point of ionization occurs between fragmented bonds. It occurs exactly between the carbon atom of the phthalate ring with the caboxylate ion group and it was also found to be most abundance one. The peak associated with m/Z 122.06 may be due to the fragmentation of C6H5COOH+ ion. The fragmentation at m/Z 154.108 has been observed due to the removal of dicarboxlic acid group from the molecule C6H5COOH CO+ ion. The deviation from the proposed molecular weight of the crystalline compound m/Z at 397.78 shall be attributed to the presence of fractional impurities in the crystal. The successive fragmentations of the molecular ion are clearly shown in the Table.10 3.4 Thermal analyses Thermo gravimetric (TGA) and differential thermal analyses (DTA) of the DLDP crystal were carried out using NETSZCH STA 409C thermal analyser in the temperature range 30°-800°C in the nitrogen atmosphere and the heating rate was fixed @ 10°C/min. The results obtained from DTA and TGA traces are shown in Fig.5. The low temperature weight loss occurs in the range 100-125°C may be due to the removal of water molecule. This can be confirmed through an endothermic event observed at 125°C in the DTA curve. A weight loss in the temperature range 175-200°C may be attributed to the partial decomposition of DLDP and it is also supported by a thermal event at 203°C in the DTA curve. An endothermic peak at 466°C followed by a curve due to the exothermic reaction confirms the complete decomposition of DLDP. Hence, the compound is thermally stable up to 203°C and the title crystal is viable for optical applications only upto this regime . 3.5 UV-Vis-NIR studies Optical transmission spectrum was recorded for DLDP compound in the wavelength range of 200 – 1200 nm and is shown in the Fig.6. It is observed that the DLDP crystal posses an absorption of 2% in the visible region. The lower UV λ cut-off wavelength occurs at 200 nm. The material is found to be transparent to all radiations in the wavelength range 400–1000 nm. The steep decrease in the transmittance of the
8 compound around 290 nm may be assigned to the electronic excitations in COO- group. As there is no appreciable change in the transmittance in the entire visible and NIR range upto 1200 nm, the material can be useful as optical windows in the spectral instruments in the wavelength range studied. 3.6. Fluorescence studies Fluorescence may be expected generally in molecules that are aromatic or contain multiple conjugated double bonds with a high degree of resonance stability [22]. The sample was excited at 200 nm and the emission spectrum as shown in Fig. 7 was measured in the range 200–400 nm. The observed peak at 389 nm in the emission spectrum indicates that DLDP crystals have a far UV fluorescence emission. 4. Conclusion The title compound Di-lithium Di-phthalate was successfully synthesized from aqueous solution using slow evaporation technique. Good quality single crystal of DLDP was been grown from the conventional slow cooling technique. Single crystal XRD measurement reveals that the grown crystal belongs to the monoclinic system with a space group of P2/n. FTIR measurements confirmed the formation of the compound and the presence of various functional groups in the DLDP crystal. The vibrational structure of the molecule has also been elucidated and the networks of hydrogen bonds were explained in detail. Mass spectrometric investigations of the crystal give valuable information on the possible fragmentations of the compound. The observed molecular ion peak agrees well with the molecular weight of the compound obtained from the single crystal data. Thermal study reveals that the DLDP crystal is thermally stable up to 203°C and a moderately termed as a soft substance. The observed UV-cut off wavelength at 200nm indicates that the material is a potential candidate for the third order NLO applications. However, an improvement in mechanical strength is necessary, if the crystal is to be used in devices. Acknowledgements The authors thank Sophisticated Analytical Instrumentation Facility (SAIF) Indian Institute of Technology Chennai, India for giving permission to avail Single crystal X-ray diffraction facility and Prof. Dr. Babu Varghese for fruitful suggestion and discussion.
9
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Maria M.Ilczyszyn , Austin J.Barnes and Henryk Ratajczak J. Mol., Struc., 29
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11
Fig. 1. A view of the molecular complex of the DLDP
12
Fig. 2. A view of the crystal packing diagrams of the DLDP
13
465
100
879
630
60
787
593
40 734
500
1000
1500
2000
2500
3000 -1
wavenumber (cm ) Fig. 3. FTIR spectra of DLDP single crystal
3428
0
2922
2852
1590
1385
20 1018 1170 1296
Transmittance (%)
80
3500
4000
20
100 150 200 250 300
m/Z
Fig. 4. Mass spectra of DLDP single crystal 350 397.78
355.14
40 281.05
253.02
221.05
154.10
207.06
80
341.04
167.11
60
149.28
104.02
77.09
100
122.06
68.36
Percentage(%)
14
400
15
100
0
2
203 C 0
125 C
0 0
466 C
0
631 C
60
0
722 C
-2 40
20
-4 100
200
300
400
500
600
0
Temperature C
Fig. 5. TG and DTA curve of DLDP single crystal
700
800
DTA (mW/mg)
TG% (mg)
80
16
200
4.0
296
Absorbance
3.5
3.0
2.5
2.0
200
400
600
800
1000
wavelenth(nm)
Fig. 6. UV-Vis-NIR spectra of DLDP single crystal
1200
17
389
1600000 1400000
Relavtive Intensity
1200000 1000000 800000 600000 400000 200000
200
225
250
275
300
325
350
Wavelength(nm)
Fig. 7. Fluorescent spectra of DLDP single crystal
375
400
18
Table 1. Crystal data and structure refinement for Di-lithium Diphthalate. Identification code Empirical formula Formula weight Temperature Wavelength Crystal system, space group Unit cell dimensions Volume Z, Calculated density Absorption coefficient F(000) Crystal size Theta range for data collection Limiting indices Reflections collected / Completeness to theta Absorption correction Max. And min. transmission Refinement method Data / restraints / parameters Goodness-of-fit on F2 Final R indices [I>2sigma(I)] R indices (all data) Extinction coefficient Largest diff. peak and hole
DLDP C32 H30 Li4 O21 778.32 293(2) K 0.71073 A° Monoclinic, P2/n a = 17.037(5) Å α = 90.000(5)°. b = 5.134(5) Å β = 113.195(5)°. c = 21.398(5) Å γ = 90.000(5)°. 1720.4(18) Å3 2, 1.503 Mg/m3 0.125 mm-1 804 0.30 x 0.20 x 0.20 mm 1.30 to 36.24°. -23<=h<=28, -7<=k<=8, -35<=l<=34 unique 26248 / 7861 [R(int) = 0.0223] = 25.00 100.0 % Semi-empirical from equivalents 0.952 and 0.901 Full-matrix least-squares on F2 7861 / 6 / 287 1.054 R1 = 0.0480, wR2 = 0.1306 R1 = 0.0828, wR2 = 0.1559 0.0014(5) 0.445 and -0.214 e.A-3
19
Table 2. Atomic coordinates ( x 104) and equivalent isotropicdisplacement parameters (A2 x 103) for DLDP. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor.
Atoms C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11) C(12) C(13) C(14) C(15) C(16) O(1) O(2) O(3) O(4) O(5) O(6) O(7) O(8) O(9) O(10) O(11) Li(1) Li(2)
x 5191(1) 5961(1) 5770(1) 6388(1) 7224(1) 7432(1) 6822(1) 7189(1) 3341(1) 4066(1) 4638(1) 5345(1) 5490(1) 4924(1) 4210(1) 3603(1) 4477(1) 5278(1) 7930(1) 6736(1) 2697(1) 3451(1) 3849(1) 2935(1) 3682(1) 2500 1071(1) 3516(1) 2166(1)
y 2457(2) 3586(2) 5625(2) 6877(3) 6086(3) 4059(2) 2792(2) 682(2) 8750(2) 9127(2) 11114(2) 11534(2) 9966(2) 7992(2) 7552(2) 5451(2) 3082(2) 860(2) 15(2) -312(2) 10194(2) 7172(2) 4010(2) 5111(2) 7659(2) 2933(2) 3643(2) 5319(4) 2299(4)
z 3634(1) 3550(1) 3083(1) 2934(1) 3244(1) 3702(1) 3872(1) 4399(1) 1617(1) 1389(1) 1702(1) 1548(1) 1079(1) 763(1) 912(1) 556(1) 3238(1) 4114(1) 4547(1) 4693(1) 1363(1) 2078(1) 161(1) 623(1) 3600(1) 2500 470(1) 2831(1) 545(1)
U(eq) 31(1) 26(1) 35(1) 40(1) 39(1) 32(1) 24(1) 26(1) 27(1) 23(1) 30(1) 35(1) 35(1) 31(1) 23(1) 24(1) 45(1) 51(1) 35(1) 41(1) 34(1) 48(1) 34(1) 33(1) 39(1) 31(1) 51(1) 32(1) 31(1)
20
Table 3. Bond lengths [Å] and angles [deg] for DLDP. Selected Bonds
Bond length (Å)
C(1)-O(1)
1.2202(13)
C(1)-O(2)
1.2768(16)
C(1)-C(2)
1.5087(15)
C(9)-O(6)
1.2330(14)
C(9)-O(5)
1.2568(14)
C(9)-C(10)
1.5088(14)
C(16)-O(8)
1.2140(13)
C(16)-O(7)
1.3103(13)
O(1)-Li(1)
1.906(2)
O(2)-H(2)
1.31(3)
O(4)-Li(2)#1
1.962(2)
O(4)-H(2)
1.06(3)
O(5)-Li(2)#2
1.949(2)
O(6)-Li(1)
1.836(2)
O(7)-H(7)
0.864(9)
O(8)-Li(2)
1.912(2)
O(9)-Li(1)
1.966(2)
O(9)-H(9A)
0.856(9)
O(9)-H(9B)
0.859(9)
O(10)-Li(1)
2.008(2)
O(10)-Li(1)#3
2.008(2)
O(10)-H(10A)
0.843(9)
O(11)-Li(2)
1.935(2)
O(11)-H(11A)
0.863(9)
O(11)-H(11B)
0.862(9)
Li(1)-Li(1)#3
3.182(4)
Li(2)-O(5)#4
1.949(2)
Li(2)-O(4)#5
1.962(2)
Selected atoms
Bond angle [deg]
O(1)-C(1)-O(2)
119.68(11)
O(1)-C(1)-C(2)
119.49(11)
O(2)-C(1)-C(2)
120.83(9)
O(6)-C(9)-O(5)
124.42(10)
O(6)-C(9)-C(10)
117.27(10)
21 O(5)-C(9)-C(10)
118.09(9)
C(14)-C(15)-C(16)
119.82(9)
C(10)-C(15)-C(16)
120.61(9)
O(8)-C(16)-O(7)
123.22(10)
O(8)-C(16)-C(15)
122.78(9)
C(1)-O(1)-Li(1)
156.59(12)
C(1)-O(2)-H(2)
111.4(10)
C(8)-O(4)-Li(2)#1
126.04(9)
C(8)-O(4)-H(2)
112.2(13)
Li(2)#1-O(4)-H(2)
121.4(13)
C(9)-O(5)-Li(2)#2
137.11(9)
C(9)-O(6)-Li(1)
168.65(12)
C(16)-O(7)-H(7)
111.5(13)
C(16)-O(8)-Li(2)
137.73(10)
Li(1)-O(9)-H(9A)
116.4(14)
Li(1)-O(9)-H(9B)
114.1(14)
H(9A)-O(9)-H(9B)
109(2)
Li(1)-O(10)-Li(1)#3
104.82(14)
Li(1)-O(10)-H(10A) Li(1)#3-O(10)H(10A)
104.1(12)
Li(2)-O(11)-H(11A)
131.6(16)
Li(2)-O(11)-H(11B) H(11A)-O(11)H(11B)
113.5(14)
O(6)-Li(1)-O(1)
117.22(11)
O(6)-Li(1)-O(9)
110.90(13)
O(1)-Li(1)-O(9)
99.85(10)
O(6)-Li(1)-O(10)
105.11(10)
O(1)-Li(1)-O(10)
105.03(12)
O(9)-Li(1)-O(10)
119.23(10)
O(6)-Li(1)-Li(1)#3
85.99(9)
O(1)-Li(1)-Li(1)#3
142.29(7)
O(9)-Li(1)-Li(1)#3
98.37(9)
O(10)-Li(1)-Li(1)#3
37.59(7)
O(8)-Li(2)-O(11)
110.05(12)
O(8)-Li(2)-O(5)#4
106.33(10)
O(11)-Li(2)-O(5)#4
111.34(10)
O(8)-Li(2)-O(4)#5
117.75(10)
O(11)-Li(2)-O(4)#5 O(5)#4-Li(2)O(4)#5
96.46(9)
116.9(12)
107(2)
114.65(12)
Symmetry transformations used to generate equivalent atoms: #1 x+1/2,-y,z+1/2 #2 x,y+1,z #3 -x+1/2,y,-z+1/2 #4 x,y-1,z #5 x-1/2,-y,z-1/2
22
Table 4. Anisotropic displacement parameters (A2 x 103) for DLDP. The anisotropic displacement factor exponent takes the form: -2 pi2 [ h2 a*2 U11 + ... + 2 h k a* b* U12 ] Atoms C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11) C(12) C(13) C(14) C(15) C(16) O(1) O(2) O(3) O(4) O(5) O(6) O(7) O(8) O(9) O(10) O(11) Li(1) Li(2)
U11 24(1) 25(1) 36(1) 50(1) 43(1) 28(1) 24(1) 24(1) 30(1) 23(1) 31(1) 28(1) 26(1) 28(1) 22(1) 24(1) 24(1) 26(1) 26(1) 28(1) 31(1) 54(1) 32(1) 29(1) 35(1) 26(1) 38(1) 26(1) 28(1)
U22 34(1) 26(1) 33(1) 35(1) 39(1) 35(1) 25(1) 26(1) 29(1) 23(1) 28(1) 32(1) 38(1) 31(1) 22(1) 23(1) 59(1) 67(1) 35(1) 53(1) 33(1) 55(1) 34(1) 30(1) 37(1) 32(1) 60(1) 38(1) 33(1)
U33 34(1) 24(1) 30(1) 33(1) 37(1) 33(1) 24(1) 26(1) 25(1) 23(1) 29(1) 40(1) 45(1) 38(1) 26(1) 26(1) 47(1) 62(1) 44(1) 42(1) 44(1) 39(1) 39(1) 43(1) 53(1) 36(1) 63(1) 31(1) 34(1)
U23 1(1) 1(1) 6(1) 12(1) 7(1) 4(1) 1(1) 3(1) -1(1) 2(1) -4(1) -4(1) -2(1) -5(1) 0(1) 1(1) 7(1) 30(1) 11(1) 25(1) 3(1) 20(1) -13(1) -6(1) -4(1) 0 -17(1) 6(1) -5(1)
U13 11(1) 8(1) 6(1) 12(1) 18(1) 13(1) 8(1) 7(1) 14(1) 9(1) 10(1) 9(1) 18(1) 18(1) 9(1) 9(1) 8(1) 19(1) 12(1) 13(1) 21(1) 24(1) 17(1) 19(1) 26(1) 14(1) 29(1) 11(1) 15(1)
U12 4(1) 3(1) 6(1) 2(1) -6(1) 0(1) 1(1) 1(1) -3(1) 0(1) -4(1) -8(1) -6(1) -3(1) -1(1) -1(1) 10(1) 6(1) 8(1) 7(1) 3(1) 1(1) -7(1) -8(1) -2(1) 0 -1(1) 1(1) -6(1)
23
Table 5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (A2 x 103) for DLDP. Hydrogen Atoms H(3) H(4) H(5) H(6) H(11) H(12) H(13) H(14) H(2) H(7) H(9A) H(9B) H(10A) H(11A) H(11B)
x 5205 6241 7647 7998 4546 5723 5967 5021 6084(16) 3479(10) 3239(9) 4094(10) 2579(11) 613(10) 1108(14)
y 6155 8251 6914 3521 12176 12875 10242 6940 260(50) 2810(30) 8480(40) 8750(30) 2000(30) 2870(40) 5080(30)
z 2865 2626 3144 3905 2019 1760 977 447 4458(13) -40(9) 3591(10) 3683(10) 2206(7) 452(12) 688(10)
U(eq) 42 49 47 38 36 41 42 37 99(8) 64(5) 79(6) 73(6) 60(5) 92(8) 78(7)
24
Table 6. Torsion angles [deg] for DLDP.
Atoms O(1)-C(1)-C(2)-C(3) O(2)-C(1)-C(2)-C(3) O(1)-C(1)-C(2)-C(7) O(2)-C(1)-C(2)-C(7) C(7)-C(2)-C(3)-C(4) C(1)-C(2)-C(3)-C(4) C(2)-C(3)-C(4)-C(5) C(3)-C(4)-C(5)-C(6) C(4)-C(5)-C(6)-C(7) C(5)-C(6)-C(7)-C(2) C(5)-C(6)-C(7)-C(8) C(3)-C(2)-C(7)-C(6) C(1)-C(2)-C(7)-C(6) C(3)-C(2)-C(7)-C(8) C(1)-C(2)-C(7)-C(8) C(6)-C(7)-C(8)-O(3) C(2)-C(7)-C(8)-O(3) C(6)-C(7)-C(8)-O(4) C(2)-C(7)-C(8)-O(4) O(6)-C(9)-C(10)-C(11) O(5)-C(9)-C(10)-C(11) O(6)-C(9)-C(10)-C(15) O(5)-C(9)-C(10)-C(15) C(15)-C(10)-C(11)-C(12) C(9)-C(10)-C(11)-C(12) C(10)-C(11)-C(12)-C(13) C(11)-C(12)-C(13)-C(14) C(12)-C(13)-C(14)-C(15) C(13)-C(14)-C(15)-C(10) C(13)-C(14)-C(15)-C(16) C(11)-C(10)-C(15)-C(14) C(9)-C(10)-C(15)-C(14) C(11)-C(10)-C(15)-C(16) C(9)-C(10)-C(15)-C(16) C(14)-C(15)-C(16)-O(8) C(10)-C(15)-C(16)-O(8) C(14)-C(15)-C(16)-O(7) C(10)-C(15)-C(16)-O(7) O(2)-C(1)-O(1)-Li(1) C(2)-C(1)-O(1)-Li(1) O(3)-C(8)-O(4)-Li(2)#1 C(7)-C(8)-O(4)-Li(2)#1 O(6)-C(9)-O(5)-Li(2)#2
Torsion angles 10.57(16) -169.32(12) -168.12(11) 11.99(18) -0.50(17) -179.34(11) 1.1(2) -0.4(2) -0.85(19) 1.43(17) -178.33(11) -0.74(15) 177.90(10) 178.98(10) -2.38(17) -10.79(14) 169.48(11) 167.19(11) -12.54(16) -92.58(14) 82.16(13) 84.65(14) -100.61(14) -0.26(16) 177.13(10) -0.15(18) 0.37(19) -0.19(18) -0.22(16) 178.84(10) 0.44(15) -176.73(10) -178.61(9) 4.22(15) -173.86(10) 5.18(15) 5.71(14) -175.25(9) 108.0(3) -71.9(3) 15.99(18) -161.93(11) -163.77(12)
25 C(10)-C(9)-O(5)-Li(2)#2 O(5)-C(9)-O(6)-Li(1) C(10)-C(9)-O(6)-Li(1) O(7)-C(16)-O(8)-Li(2) C(15)-C(16)-O(8)-Li(2) C(9)-O(6)-Li(1)-O(1) C(9)-O(6)-Li(1)-O(9) C(9)-O(6)-Li(1)-O(10) C(9)-O(6)-Li(1)-Li(1)#3 C(1)-O(1)-Li(1)-O(6) C(1)-O(1)-Li(1)-O(9) C(1)-O(1)-Li(1)-O(10) C(1)-O(1)-Li(1)-Li(1)#3 Li(1)#3-O(10)-Li(1)-O(6) Li(1)#3-O(10)-Li(1)-O(1) Li(1)#3-O(10)-Li(1)-O(9) C(16)-O(8)-Li(2)-O(11) C(16)-O(8)-Li(2)-O(5)#4 C(16)-O(8)-Li(2)-O(4)#5
21.90(18) -37.8(6) 136.5(5) 26.10(19) -154.37(12) -146.2(5) -32.5(6) 97.6(6) 64.9(6) 94.0(3) -25.8(3) -149.8(2) -143.6(2) -62.01(8) 173.73(12) 63.05(10) -162.50(11) 76.79(16) -53.39(19)
Symmetry transformations used to generate equivalent atoms: #1 x+1/2,-y,z+1/2 #2 x,y+1,z #3 -x+1/2,y,-z+1/2 #4 x,y-1,z #5 x-1/2,-y,z-1/2
26 Table 7. Hydrogen bonds for DLDP [Å and deg.]. D-H...A O(4)-H(2)...O(2) O(7)-H(7)...O(3)#5 O(9)-H(9A)...O(5)#3 O(9)-H(9B)...O(2)#2 O(10)-H(10A)...O(5)#4 O(11)-H(11A)...O(2)#3 O(11)-H(11B)...O(9)#3
d(D-H) 1.06(3) 0.864(9) 0.856(9) 0.859(9) 0.843(9) 0.863(9) 0.862(9)
d(H...A) 1.31(3) 1.764(10) 1.859(10) 2.152(11) 2.107(9) 2.311(13) 1.944(11)
d(D...A) 2.3764(13) 2.612(2) 2.7141(15) 2.9906(17) 2.9416(13) 3.1194(17) 2.781(2)
<(DHA) 174(2) 166.8(19) 176(2) 165.4(19) 170.4(18) 156(2) 164(2)
Symmetry transformations used to generate equivalent atoms: #1 x+1/2,-y,z+1/2 #2 x,y+1,z #3 -x+1/2,y,-z+1/2 #4 x,y-1,z #5 x-1/2,-y,z-1/2
Table 8. Tetrahedral Bonds length[Å] and angle [deg] Tetrahedral Bonds
Bond length (Å)
O(1)-Li(1)
1.906(2)
O(6)-Li(1)
1.836(2)
O(9)-Li(1)
1.966(2)
O(10)-Li(1)
2.008(2)
tetrahedra atoms
Bond angle [deg]
O(6)-Li(1)-O(1)
117.22(11)
O(6)-Li(1)-O(9)
110.90(13)
O(1)-Li(1)-O(9)
99.85(10)
O(6)-Li(1)-O(10)
105.11(10)
O(1)-Li(1)-O(10)
105.03(12)
O(9)-Li(1)-O(10)
119.23(10)
27
Table 9: FTIR assignments of DLDP Wavenumber(cm-1)
Assignments
3428
OH-stretching hydrogen bond
2922
OH stretching intermolecule
2852
C-H stretching in ring
1590
Ring structure
1385
C-O stretching
1296
C-C-O asymmetric stretching
1170
OH stretching hydrogen bond overtone
1018
C-O stretching (COOH group)
879
OH overtone
787 630
Four adjacent hydrogen in phase out-ofplane vibration C-O wagging
593
Alkali metal vibration in acid group
465
Out of plane ring bending in meta position
28
Table 10. Nature of fragmentation of DLDP. S.No m/Z 1 397.78
2
355.144
3
207.062
4
167.113
Nature of fragmentation
29 5
122.065
6
104.026
7
77.0965
30
Gr ap hic al ab str act
1. A view of the molecular comlex of Df DLDP is shown above
The vibrational structure of the compound confirms the presence of various functional groups in the molecule. 3. Mass spectrometric analysis provides the molecular weight of the compound and possible ways of 2.
31
fragmentations occurring in the compound. 4. Thermal stability of the crystal was also studied by simultaneous TGA/DTA analyses. 5. The UV-Vis-NIR spectrum was recorded to study the transmittance properties of the grown crystals.
32 HIGHLIGHTS • • •
•
New optical Di-Lithium Di-phthalate single crystals is synthesized. The crystal is a potential candidate for the third order NLO applications. The grown crystals were subjected to X-ray diffraction, FTIR, Mass spectral analysis, Thermo gravimetric and differential thermal analyses and UV-VIS-NIR studies to characterize the crystal. On improving mechanical strength, the crystal can be used in devices.
S1386-1425(15)00724-6 http://dx.doi.org/10.1016/j.saa.2015.06.010 SAA 13779
To appear in:
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Received Date: Revised Date: Accepted Date:
22 July 2014 3 June 2015 6 June 2015
Please cite this article as: D. Saravanan, G. Ramesh Kumar, S. Gokul Raj, S. Mohan, B. Sivakumar, Synthesis, crystal structure and characterization of a new optical di-lithium di-phthalate single crystals, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (2015), doi: http://dx.doi.org/10.1016/j.saa.2015.06.010
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1
Synthesis, Crystal structure and Characterization of a new optical Di-Lithium Di-phthalate single crystals
1
D. Saravanan1, G. Ramesh Kumar2, S. Gokul Raj3, S. Mohan3,*, B. Sivakumar4 Department of Physics, Sri Venkateshawaraa College of Engineering & Technology, Ariyur - 605102, India 2 Department of Physics, University College of Engineering Arni, Anna University Chennai, Arni -632317. India. 3 Department of Physics, Vel Tech University, Avadi, Chennai -600 062, India. 4 Department of Physics, University College of Engineering Kanchipuram, Anna University Chennai, Kanchipuram - 631552. India.
* Corresponding author: Prof. S. Mohan ([email protected])
Abstract: Single crystals of a new alkali phthalic complex salt of Di-lithium Di-phthalate (C32 H30 Li4 O21) (DLDP) were grown by slow evaporation of an aqueous solution at room temperature. The compound crystallizes in a monoclinic system with a centrosymmetric space group having the unit cell parameters; a= 17.037(5) Å, b= 5.134(5) Å, and c=21.398(5) Å and α = 90.000(5) °, β = 113.195(5) °, and γ = 90.000(5) ° with Z= 2. The structure has been refined upto a R-value of 0.0828 from 26248 observed reflections using a three-dimensional X-ray diffraction intensity data. The vibrational structure of the compound confirms the presence of various functional groups in the molecule. Mass spectrometric analysis provides the molecular weight of the compound and possible ways of fragmentations occurring in the compound. Thermal stability of the crystal was also studied by simultaneous TGA/DTA analyses. The UV-VIS-NIR spectrum was recorded to study the transmittance properties of the grown crystals. The obtained results are discussed in detail.
Keywords: Di-Lithium Diphthalate ; Single crystal; Hydrogen bonds; FT-IR; UV-Vis-NIR; Mass spectrometry;
2 1. Introduction Synthesizing metallo-organic crystals have been reported as a new approach for materials with interesting nonlinear optical properties [1-4]. In metallo-organics, polarizable organic molecules are stoichiometrically bound with in an inorganic host [5]. The advantage of metallo-organic materials is that the crystal can be grown from aqueous solution and they form three-dimensional crystals which can be easily cut and polished [6]. The other favourable properties are high optical damage threshold, large thermal conductivity, adequate birefringence for phase matching and good mechanical characteristics.
The low-temperature solution growth is an important technique for
growing large-size nonlinear optical crystals. The crystals grown by this technique find wide spread applications in key areas like inertial confinement fusion [6], X-ray spectroscopy and laser energy measurement [7] etc., In order to grow large crystal, one has to ensure that the available nutrient is deposited on the chosen seed only during the growth period. Otherwise, any spontaneous nucleation occurring during the growth will take away a portion of the solute, thus making it difficult or impossible to grow a single large crystal. Although crystals of different orientations with different morphology are grown by conventional solution growth technique,
the specific orientation with good
quality is needed for applications. Several metallo-organic large-size good-quality single crystals such as Potassium acid phthalate (KAP), Sodium acid phthalate (NaAP) and Lithium acid Phthalate (LiAP) were successfully grown by this method [8-11]. Crystals of phthalic acid derivatives are potential candidates for NLO and electro-optic processes [12]. Rubidium acid phthalate (RbAP), Cesium acid phthalate (CsAP), Thallium acid phthalate(TiAP) and Ammonium acid phthalate(NH4AP) are well-known reported metallo-organic phthalic acid crystals. The inorganic hydrogen phthalate crystals are widely known for their applications in the long-wave X-ray spectrometers. Their optical, piezo-electric, NLO and elastic properties were already reported by Belyeav et al, [13]. In the present investigation, a new mixed Lithium Phthalate single crystal has been grown by the conventional slow cooling technique. The preliminary X-ray structure investigation revealed that the colourless crystals of Di-lithium Di-phthalate (DLDP) have unit cell parameters that differ from those of other Alkali acid phthalate crystals. Optical properties of acid phthalate crystals
3 were been reported in literature [9]. However, no study has been made so far on the new crystals of DLDP. Hence, the grown crystals of DLDP are subjected to various studies like single-crystal X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and Simultaneous TG and DTA analyses. UV-VIS-NIR absorption spectrum was also recorded for the title compound.
2. Experimental procedure 2.1. Crystal growth Di-lithium Di-phthalate was synthesized by the reaction between phthalic acid (EMerck 99.9%) and lithium Hydroxide (LOBO 99%) taken in an equimolar ratio 1:1. The reactants were thoroughly dissolved in double distilled water and stirred using a temperature controlled magnetic stirrer to get a homogeneous mixture of the solution. Then, the solution was allowed to evaporate at room temperature which yields crystalline salt of Di-lithium Diphthalate. The process of recrystallization was carried out to purify the synthesized salt. The reaction mechanism of DLDP is shown below.
Phthalic acid + Lithium hydroxide
Di-lithium Diphthalate
Scheme of reaction of DLDP
2.2 Characterization studies
4 The grown crystals of DLDP have been subjected to single crystal X-ray diffraction. The FTIR spectrum was recorded in the frequency range 400-4000cm-1 by employing Bruker IFS66 FTIR spectrometer using KBr pellet method. Mass spectral analysis was carried out using a JEOL GC mate mass spectrometer for confirming the formation of new title compound. Thermo gravimetric and differential thermal analyses were also carried out using NETSZCH STA 409C thermal analyzer. Optical absorption properties of the crystals were studied using a Varion Cary 5E UV-VIS-NIR spectrophotometer. The emission spectrum was recorded using JOBIN YVON Spectrofluorometer in wavelength range 200-400nm. 3. Results and discussion 3.1 Single crystal X-ray diffraction analysis The unit cell dimension and X-ray intensity data of DLDP was obtained on a Enraf Nonius CAD 4 Bruker Kappa APEX II single crystal X-ray diffractometer equipped with MoKα radiation (λ=0.71073 Å). ω/2θ scan mode was employed for data collection [14]. The dimension of the crystal used for the measurements was 0.30x0.20x0.20 mm3. A total of 26248 reflections were measured, out of which 7861 were found unique and its limiting indices were -23<=h<=28, -7<=k<=8, and 35<=l<=34. For the structure solution and refinement, the lattice parameters were refined for all the collected reflections. The estimated standard deviation (esd) was calculated using full variance-covariance matrix method for bond length and bond angle. Integrated intensities were reduced for Lorenz, polarization and decay corrections. Absorption corrections were employed based on
psi-scan mode [15]. The maximum and minimum
transmission factors were 0.95 and 0.90. The crystal structure was solved by direct method using SIR92 (WINGX)[16] and refinement was done by using SHELXL 97[17]. The hydrogen atoms of phthalic acid ring were located by difference Fourier map and was refined with isotropic thermal parameters. The crystallographic refinement parameters are listed in Table.1. The atomic coordinates and isotropic displacement parameters are listed in Table.2. The bond lengths and bond angles are listed in Table 3. Non-hydrogen atoms were refined with anisotropic displacement parameters whose values are provided in the Table.4. Other hydrogen atoms were fixed at meaningful
5 positions and were given riding model refinement. The refinement was continued until maximum shift was zero. The final refinement factor(R) was 0.0828. It was observed that the compound DLDP crystallizes in an Monoclinic crystal system with a centrosymmetric space group of P2/n. The unit cell parameters were found to be a = 17.037(5) Å; b = 5.134(5) Å and c = 21.398(5) Å .and α = 90.000(5) °; β = 113.195(5) °;γ = 90.000(5) ° and V= 1720.4 (18) Å3. Fig.1 shows the ORTEP (50% probability ellipsoid) representation of the molecule with numbering scheme. The unit cell pack up of DLDP is also shown in Fig 2. Hydrogen coordinates and isotropic displacement parameters are listed in the Table 5. The Torsion angles are listed in the Table 6. The various hydrogen bond parameters are listed in Table 7. From the ORTEP representation, it is perceived that the Li ions are coordinated by four O- atoms which form a slightly distorted tetrahedral fashion. The bond distances and bond angles of DLDP range from 1.839(2) Å- 2.008(2) Å and 99°-119° respectively. Li (1) is connected to the two oxygen of H2O molecules and the remaining two with the inner O atoms of the both carboxylic groups of the both phthalate ions, whereas Li (2) is connected to the oxygen and the remaining with the inner O atom of the carboxylic groups of one of the phthalic ions. Further, O (11) atoms are less ionized because they form an intramolecular hydrogen bond with O(4) atom bond distance of Li(1)-O was found to be longer and as the consequence the tetrahedron structure got more distorted. The
distance Li(1)-O(1), Li(1)-O(10), Li(1)-O(9), and Li(1)-O(6), are equal
within the tetrahedral bond distance of range 1.836(2) Å to 2.008(2) Å . O(10) and O(9) are involved in the hydrogen bonds with the water molecules. Hence, H(1) should be more closely attached to the O(4) than to O(2) because O(2) shows no interamolecular linkage. In a molecule of lowered symmetry with respect to linked neighbor, it is difficult to decide whether O(4) or O(3) is closer to the hydrogen. Bond distances and the corresponding angles in these tetrahedral connected Li atom of DLDP are given in the Table 8. The Li (1) ion occupies a position with an ionic contact between two phthalate ions and they are mutually interconnected by the strong ionic bonds between O (6) and Li
6 (1). Further, linkage is mainly achieved by a complicated frame work of seven O-H…O hydrogen bonds which are listed in Table.7. The water molecules are mutually interconnected by strong O-H..O hydrogen bonds forming infinite chains along the ‘ab’ direction. The tetrahedral co-ordination of Li 1 are linked along the ‘b’ direction by hydrogen bonds which are the connecting the edge of O(9)-H(9)-O(2) atoms with O(10) –H(10)-O(5) of the neighboring cell above and below the cell drawn in ORTEP via H(9) and H(10). The oxygen of three water molecules namely O(9), O(10) and O(11) are held in a rigid position by their contact with the Li ion through strong hydrogen bonds. Consequently, the positions of hydrated molecules can not be well defined due to the temperature factors. In case of Nickel diphthalate (NiDP) and Potassium diphthalate (KDIP) [18, 19], a regular octahedral network were observed wherein the bond distance of octahedraly positioned potassium ion with the oxygen atom vary from 2.805-2.986Å. All this metal organic complexes having a tetrahedral as well as octahedral metal ion occupies a special position with a site symmetry ī and hence the crystals are centric in nature. 3.2 Fourier transform infrared spectroscopy ( FTIR ) Fourier transform infrared (FTIR) spectrum of DLDP was recorded in the frequency range of 400 – 4000 cm-1 by KBr pellet method and is shown in Fig 3. A broad shoulder at 3428 cm-1 is due to OH stretching vibrations of the water molecule. A peak at 593 cm-1 is due to alkali metal stretching of the acid group. Similar vibrations also observed for KAP[20] . The aromatic ring is indicated by a peak at 1590 cm-1. The presence of carboxyl group can be identified from the appearance of bands at 1381, 428 and 548 cm-1 which correspond to symmetric stretching, rocking and wagging vibrations of COO- respectively. From X-ray data it was found that the entire molecule is stabilized by the three dimensional network of H-bonds and framed by seven O-H..O type strong hydrogen bonds. The broad shoulders around 3400, 1600 and 800 cm-1 are due to the fundamental vibrations and overtones of the hydrated molecules. The other vibrations for the phthalic acid group and that for the lithium with phthalate molecules are assigned in Table 9 which agree well with the reported values for other phthalate groups [21].
7 3.3 Mass spectrometry of DLDP Mass spectrometry was carried out for DLDP in the m/Z range 50 - 400 amu is shown in Fig.4. Since, the Phthalic acid molecule contains aromatic rings, a molecular ion peak could be observed at m/Z 77. The base peak at m/Z 104.24 corresponds to the C6H5CO+ ion and it clearly shows that the preferential point of ionization occurs between fragmented bonds. It occurs exactly between the carbon atom of the phthalate ring with the caboxylate ion group and it was also found to be most abundance one. The peak associated with m/Z 122.06 may be due to the fragmentation of C6H5COOH+ ion. The fragmentation at m/Z 154.108 has been observed due to the removal of dicarboxlic acid group from the molecule C6H5COOH CO+ ion. The deviation from the proposed molecular weight of the crystalline compound m/Z at 397.78 shall be attributed to the presence of fractional impurities in the crystal. The successive fragmentations of the molecular ion are clearly shown in the Table.10 3.4 Thermal analyses Thermo gravimetric (TGA) and differential thermal analyses (DTA) of the DLDP crystal were carried out using NETSZCH STA 409C thermal analyser in the temperature range 30°-800°C in the nitrogen atmosphere and the heating rate was fixed @ 10°C/min. The results obtained from DTA and TGA traces are shown in Fig.5. The low temperature weight loss occurs in the range 100-125°C may be due to the removal of water molecule. This can be confirmed through an endothermic event observed at 125°C in the DTA curve. A weight loss in the temperature range 175-200°C may be attributed to the partial decomposition of DLDP and it is also supported by a thermal event at 203°C in the DTA curve. An endothermic peak at 466°C followed by a curve due to the exothermic reaction confirms the complete decomposition of DLDP. Hence, the compound is thermally stable up to 203°C and the title crystal is viable for optical applications only upto this regime . 3.5 UV-Vis-NIR studies Optical transmission spectrum was recorded for DLDP compound in the wavelength range of 200 – 1200 nm and is shown in the Fig.6. It is observed that the DLDP crystal posses an absorption of 2% in the visible region. The lower UV λ cut-off wavelength occurs at 200 nm. The material is found to be transparent to all radiations in the wavelength range 400–1000 nm. The steep decrease in the transmittance of the
8 compound around 290 nm may be assigned to the electronic excitations in COO- group. As there is no appreciable change in the transmittance in the entire visible and NIR range upto 1200 nm, the material can be useful as optical windows in the spectral instruments in the wavelength range studied. 3.6. Fluorescence studies Fluorescence may be expected generally in molecules that are aromatic or contain multiple conjugated double bonds with a high degree of resonance stability [22]. The sample was excited at 200 nm and the emission spectrum as shown in Fig. 7 was measured in the range 200–400 nm. The observed peak at 389 nm in the emission spectrum indicates that DLDP crystals have a far UV fluorescence emission. 4. Conclusion The title compound Di-lithium Di-phthalate was successfully synthesized from aqueous solution using slow evaporation technique. Good quality single crystal of DLDP was been grown from the conventional slow cooling technique. Single crystal XRD measurement reveals that the grown crystal belongs to the monoclinic system with a space group of P2/n. FTIR measurements confirmed the formation of the compound and the presence of various functional groups in the DLDP crystal. The vibrational structure of the molecule has also been elucidated and the networks of hydrogen bonds were explained in detail. Mass spectrometric investigations of the crystal give valuable information on the possible fragmentations of the compound. The observed molecular ion peak agrees well with the molecular weight of the compound obtained from the single crystal data. Thermal study reveals that the DLDP crystal is thermally stable up to 203°C and a moderately termed as a soft substance. The observed UV-cut off wavelength at 200nm indicates that the material is a potential candidate for the third order NLO applications. However, an improvement in mechanical strength is necessary, if the crystal is to be used in devices. Acknowledgements The authors thank Sophisticated Analytical Instrumentation Facility (SAIF) Indian Institute of Technology Chennai, India for giving permission to avail Single crystal X-ray diffraction facility and Prof. Dr. Babu Varghese for fruitful suggestion and discussion.
9
References [1]
M.D. Aggarwal, J. Stephens, A.K. Batra, R.B. Lal, J. Optoelectron. Adv. Mater. 5
(2003) 555 – 562. [2]
S. Debrus, H. Ratajczak, J. Venturini, N. Pincon, J. Baran, J. Barycki, T. Glowiak,
A. Pietraszko, Synth. Met. 127 (2002) 99 – 104. [3]
G.M. Loiacono, W.N Osborne J.Cryst, Growth 43(1978) 401 - 405.
[4]
N. kejalakshmy, K.Srinivasan, Opt. Mater 27 (2004) 389 – 394.
[5]
J. Qin, D. Liu, C. Dai, C. Chen, B. Wu, C. Yang, C. Zhan, Coord. Chem. Rev.
188 (1999) 23 – 34. [6]
N.Saitseva, J. Atherton, R.Rozsa, L.Carman, I.Smolksy, M,Runkel R.Ryon L.James, J.Cryst.Growth 197 (1999) 911 – 920.
[7]
S.Satapathy, S.K.Sharma, A.K.Karnal, V.K.Wadhawan, J.Cryst.Growth 240
(2002) 196 – 202. [8]
N.Balamurugan M.Lenin, P.Ramasamy Materials Letters 61(2007) 1896 – 1898.
[9]
A.Senthil P.Ramasamy, J. Cryst.Growth 311(2009) 4720 – 4724.
[10]
K.Krishnan, C.Justin Raj, S.Dinakaran, R. Uthrakumar, R.Robert, S.Jerome Das J. Phys.Chem Of Solids 69(2008) 2883 – 2887.
[11]
A.Senthil P.Ramasamy, G.Bhagavannarayana, J.Cryst. Growth. 311(2009) 2696 –
2701. [12]
Monica Enculesu Opt. Materials 32 (2009) 281 – 285.
[13]
L.M Belyeav, G.S.Belikova, A.B. Gilvarg, I.M Silvastrova, Sov.Phys,
Crystallogr. 14(1970) 544 – 549. [14]
Bruker (2004). APEX2, SADABS, XPREP and SAINT-Plus. Bruker AXS Inc., Madison, Wisconsin, USA.
[15]
Altomare, A., Cascarano, G., Giacovazzo, C. & Guagliardi, A. (1993). J. Appl.
Cryst. 26, 343 – 350. [16]
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.
[17]
Sheldrick, G. M. (1997). SHELXL97. University of Gottingen, Germany
[18]
Adiwidjaja, G., and Kuppers, H., Acta Cryst. B32, (1976) 1571 – 1574.
10 [19]
Benedict, Jason B., Theresa Bullard, Wener Kaminsky, and BartKahr (2004) Acta
Cryt. C60, m551 – m553. [20]
B.Orel, Hadzi and C.Cabassi Spectrochimia Acta 31A (1975) 169 – 182.
[21]
Maria M.Ilczyszyn , Austin J.Barnes and Henryk Ratajczak J. Mol., Struc., 29
(1993) 135 – 143. [22]
H.H. Willard, L.L. Merritt Jr., J.A. Dean, F.A. Settle Jr., Instrumental Methods of Analysis, sixth ed., Wadsworth Publishing Company, USA, 1986, p. 609.
11
Fig. 1. A view of the molecular complex of the DLDP
12
Fig. 2. A view of the crystal packing diagrams of the DLDP
13
465
100
879
630
60
787
593
40 734
500
1000
1500
2000
2500
3000 -1
wavenumber (cm ) Fig. 3. FTIR spectra of DLDP single crystal
3428
0
2922
2852
1590
1385
20 1018 1170 1296
Transmittance (%)
80
3500
4000
20
100 150 200 250 300
m/Z
Fig. 4. Mass spectra of DLDP single crystal 350 397.78
355.14
40 281.05
253.02
221.05
154.10
207.06
80
341.04
167.11
60
149.28
104.02
77.09
100
122.06
68.36
Percentage(%)
14
400
15
100
0
2
203 C 0
125 C
0 0
466 C
0
631 C
60
0
722 C
-2 40
20
-4 100
200
300
400
500
600
0
Temperature C
Fig. 5. TG and DTA curve of DLDP single crystal
700
800
DTA (mW/mg)
TG% (mg)
80
16
200
4.0
296
Absorbance
3.5
3.0
2.5
2.0
200
400
600
800
1000
wavelenth(nm)
Fig. 6. UV-Vis-NIR spectra of DLDP single crystal
1200
17
389
1600000 1400000
Relavtive Intensity
1200000 1000000 800000 600000 400000 200000
200
225
250
275
300
325
350
Wavelength(nm)
Fig. 7. Fluorescent spectra of DLDP single crystal
375
400
18
Table 1. Crystal data and structure refinement for Di-lithium Diphthalate. Identification code Empirical formula Formula weight Temperature Wavelength Crystal system, space group Unit cell dimensions Volume Z, Calculated density Absorption coefficient F(000) Crystal size Theta range for data collection Limiting indices Reflections collected / Completeness to theta Absorption correction Max. And min. transmission Refinement method Data / restraints / parameters Goodness-of-fit on F2 Final R indices [I>2sigma(I)] R indices (all data) Extinction coefficient Largest diff. peak and hole
DLDP C32 H30 Li4 O21 778.32 293(2) K 0.71073 A° Monoclinic, P2/n a = 17.037(5) Å α = 90.000(5)°. b = 5.134(5) Å β = 113.195(5)°. c = 21.398(5) Å γ = 90.000(5)°. 1720.4(18) Å3 2, 1.503 Mg/m3 0.125 mm-1 804 0.30 x 0.20 x 0.20 mm 1.30 to 36.24°. -23<=h<=28, -7<=k<=8, -35<=l<=34 unique 26248 / 7861 [R(int) = 0.0223] = 25.00 100.0 % Semi-empirical from equivalents 0.952 and 0.901 Full-matrix least-squares on F2 7861 / 6 / 287 1.054 R1 = 0.0480, wR2 = 0.1306 R1 = 0.0828, wR2 = 0.1559 0.0014(5) 0.445 and -0.214 e.A-3
19
Table 2. Atomic coordinates ( x 104) and equivalent isotropicdisplacement parameters (A2 x 103) for DLDP. U(eq) is defined as one third of the trace of the orthogonalized Uij tensor.
Atoms C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11) C(12) C(13) C(14) C(15) C(16) O(1) O(2) O(3) O(4) O(5) O(6) O(7) O(8) O(9) O(10) O(11) Li(1) Li(2)
x 5191(1) 5961(1) 5770(1) 6388(1) 7224(1) 7432(1) 6822(1) 7189(1) 3341(1) 4066(1) 4638(1) 5345(1) 5490(1) 4924(1) 4210(1) 3603(1) 4477(1) 5278(1) 7930(1) 6736(1) 2697(1) 3451(1) 3849(1) 2935(1) 3682(1) 2500 1071(1) 3516(1) 2166(1)
y 2457(2) 3586(2) 5625(2) 6877(3) 6086(3) 4059(2) 2792(2) 682(2) 8750(2) 9127(2) 11114(2) 11534(2) 9966(2) 7992(2) 7552(2) 5451(2) 3082(2) 860(2) 15(2) -312(2) 10194(2) 7172(2) 4010(2) 5111(2) 7659(2) 2933(2) 3643(2) 5319(4) 2299(4)
z 3634(1) 3550(1) 3083(1) 2934(1) 3244(1) 3702(1) 3872(1) 4399(1) 1617(1) 1389(1) 1702(1) 1548(1) 1079(1) 763(1) 912(1) 556(1) 3238(1) 4114(1) 4547(1) 4693(1) 1363(1) 2078(1) 161(1) 623(1) 3600(1) 2500 470(1) 2831(1) 545(1)
U(eq) 31(1) 26(1) 35(1) 40(1) 39(1) 32(1) 24(1) 26(1) 27(1) 23(1) 30(1) 35(1) 35(1) 31(1) 23(1) 24(1) 45(1) 51(1) 35(1) 41(1) 34(1) 48(1) 34(1) 33(1) 39(1) 31(1) 51(1) 32(1) 31(1)
20
Table 3. Bond lengths [Å] and angles [deg] for DLDP. Selected Bonds
Bond length (Å)
C(1)-O(1)
1.2202(13)
C(1)-O(2)
1.2768(16)
C(1)-C(2)
1.5087(15)
C(9)-O(6)
1.2330(14)
C(9)-O(5)
1.2568(14)
C(9)-C(10)
1.5088(14)
C(16)-O(8)
1.2140(13)
C(16)-O(7)
1.3103(13)
O(1)-Li(1)
1.906(2)
O(2)-H(2)
1.31(3)
O(4)-Li(2)#1
1.962(2)
O(4)-H(2)
1.06(3)
O(5)-Li(2)#2
1.949(2)
O(6)-Li(1)
1.836(2)
O(7)-H(7)
0.864(9)
O(8)-Li(2)
1.912(2)
O(9)-Li(1)
1.966(2)
O(9)-H(9A)
0.856(9)
O(9)-H(9B)
0.859(9)
O(10)-Li(1)
2.008(2)
O(10)-Li(1)#3
2.008(2)
O(10)-H(10A)
0.843(9)
O(11)-Li(2)
1.935(2)
O(11)-H(11A)
0.863(9)
O(11)-H(11B)
0.862(9)
Li(1)-Li(1)#3
3.182(4)
Li(2)-O(5)#4
1.949(2)
Li(2)-O(4)#5
1.962(2)
Selected atoms
Bond angle [deg]
O(1)-C(1)-O(2)
119.68(11)
O(1)-C(1)-C(2)
119.49(11)
O(2)-C(1)-C(2)
120.83(9)
O(6)-C(9)-O(5)
124.42(10)
O(6)-C(9)-C(10)
117.27(10)
21 O(5)-C(9)-C(10)
118.09(9)
C(14)-C(15)-C(16)
119.82(9)
C(10)-C(15)-C(16)
120.61(9)
O(8)-C(16)-O(7)
123.22(10)
O(8)-C(16)-C(15)
122.78(9)
C(1)-O(1)-Li(1)
156.59(12)
C(1)-O(2)-H(2)
111.4(10)
C(8)-O(4)-Li(2)#1
126.04(9)
C(8)-O(4)-H(2)
112.2(13)
Li(2)#1-O(4)-H(2)
121.4(13)
C(9)-O(5)-Li(2)#2
137.11(9)
C(9)-O(6)-Li(1)
168.65(12)
C(16)-O(7)-H(7)
111.5(13)
C(16)-O(8)-Li(2)
137.73(10)
Li(1)-O(9)-H(9A)
116.4(14)
Li(1)-O(9)-H(9B)
114.1(14)
H(9A)-O(9)-H(9B)
109(2)
Li(1)-O(10)-Li(1)#3
104.82(14)
Li(1)-O(10)-H(10A) Li(1)#3-O(10)H(10A)
104.1(12)
Li(2)-O(11)-H(11A)
131.6(16)
Li(2)-O(11)-H(11B) H(11A)-O(11)H(11B)
113.5(14)
O(6)-Li(1)-O(1)
117.22(11)
O(6)-Li(1)-O(9)
110.90(13)
O(1)-Li(1)-O(9)
99.85(10)
O(6)-Li(1)-O(10)
105.11(10)
O(1)-Li(1)-O(10)
105.03(12)
O(9)-Li(1)-O(10)
119.23(10)
O(6)-Li(1)-Li(1)#3
85.99(9)
O(1)-Li(1)-Li(1)#3
142.29(7)
O(9)-Li(1)-Li(1)#3
98.37(9)
O(10)-Li(1)-Li(1)#3
37.59(7)
O(8)-Li(2)-O(11)
110.05(12)
O(8)-Li(2)-O(5)#4
106.33(10)
O(11)-Li(2)-O(5)#4
111.34(10)
O(8)-Li(2)-O(4)#5
117.75(10)
O(11)-Li(2)-O(4)#5 O(5)#4-Li(2)O(4)#5
96.46(9)
116.9(12)
107(2)
114.65(12)
Symmetry transformations used to generate equivalent atoms: #1 x+1/2,-y,z+1/2 #2 x,y+1,z #3 -x+1/2,y,-z+1/2 #4 x,y-1,z #5 x-1/2,-y,z-1/2
22
Table 4. Anisotropic displacement parameters (A2 x 103) for DLDP. The anisotropic displacement factor exponent takes the form: -2 pi2 [ h2 a*2 U11 + ... + 2 h k a* b* U12 ] Atoms C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11) C(12) C(13) C(14) C(15) C(16) O(1) O(2) O(3) O(4) O(5) O(6) O(7) O(8) O(9) O(10) O(11) Li(1) Li(2)
U11 24(1) 25(1) 36(1) 50(1) 43(1) 28(1) 24(1) 24(1) 30(1) 23(1) 31(1) 28(1) 26(1) 28(1) 22(1) 24(1) 24(1) 26(1) 26(1) 28(1) 31(1) 54(1) 32(1) 29(1) 35(1) 26(1) 38(1) 26(1) 28(1)
U22 34(1) 26(1) 33(1) 35(1) 39(1) 35(1) 25(1) 26(1) 29(1) 23(1) 28(1) 32(1) 38(1) 31(1) 22(1) 23(1) 59(1) 67(1) 35(1) 53(1) 33(1) 55(1) 34(1) 30(1) 37(1) 32(1) 60(1) 38(1) 33(1)
U33 34(1) 24(1) 30(1) 33(1) 37(1) 33(1) 24(1) 26(1) 25(1) 23(1) 29(1) 40(1) 45(1) 38(1) 26(1) 26(1) 47(1) 62(1) 44(1) 42(1) 44(1) 39(1) 39(1) 43(1) 53(1) 36(1) 63(1) 31(1) 34(1)
U23 1(1) 1(1) 6(1) 12(1) 7(1) 4(1) 1(1) 3(1) -1(1) 2(1) -4(1) -4(1) -2(1) -5(1) 0(1) 1(1) 7(1) 30(1) 11(1) 25(1) 3(1) 20(1) -13(1) -6(1) -4(1) 0 -17(1) 6(1) -5(1)
U13 11(1) 8(1) 6(1) 12(1) 18(1) 13(1) 8(1) 7(1) 14(1) 9(1) 10(1) 9(1) 18(1) 18(1) 9(1) 9(1) 8(1) 19(1) 12(1) 13(1) 21(1) 24(1) 17(1) 19(1) 26(1) 14(1) 29(1) 11(1) 15(1)
U12 4(1) 3(1) 6(1) 2(1) -6(1) 0(1) 1(1) 1(1) -3(1) 0(1) -4(1) -8(1) -6(1) -3(1) -1(1) -1(1) 10(1) 6(1) 8(1) 7(1) 3(1) 1(1) -7(1) -8(1) -2(1) 0 -1(1) 1(1) -6(1)
23
Table 5. Hydrogen coordinates ( x 104) and isotropic displacement parameters (A2 x 103) for DLDP. Hydrogen Atoms H(3) H(4) H(5) H(6) H(11) H(12) H(13) H(14) H(2) H(7) H(9A) H(9B) H(10A) H(11A) H(11B)
x 5205 6241 7647 7998 4546 5723 5967 5021 6084(16) 3479(10) 3239(9) 4094(10) 2579(11) 613(10) 1108(14)
y 6155 8251 6914 3521 12176 12875 10242 6940 260(50) 2810(30) 8480(40) 8750(30) 2000(30) 2870(40) 5080(30)
z 2865 2626 3144 3905 2019 1760 977 447 4458(13) -40(9) 3591(10) 3683(10) 2206(7) 452(12) 688(10)
U(eq) 42 49 47 38 36 41 42 37 99(8) 64(5) 79(6) 73(6) 60(5) 92(8) 78(7)
24
Table 6. Torsion angles [deg] for DLDP.
Atoms O(1)-C(1)-C(2)-C(3) O(2)-C(1)-C(2)-C(3) O(1)-C(1)-C(2)-C(7) O(2)-C(1)-C(2)-C(7) C(7)-C(2)-C(3)-C(4) C(1)-C(2)-C(3)-C(4) C(2)-C(3)-C(4)-C(5) C(3)-C(4)-C(5)-C(6) C(4)-C(5)-C(6)-C(7) C(5)-C(6)-C(7)-C(2) C(5)-C(6)-C(7)-C(8) C(3)-C(2)-C(7)-C(6) C(1)-C(2)-C(7)-C(6) C(3)-C(2)-C(7)-C(8) C(1)-C(2)-C(7)-C(8) C(6)-C(7)-C(8)-O(3) C(2)-C(7)-C(8)-O(3) C(6)-C(7)-C(8)-O(4) C(2)-C(7)-C(8)-O(4) O(6)-C(9)-C(10)-C(11) O(5)-C(9)-C(10)-C(11) O(6)-C(9)-C(10)-C(15) O(5)-C(9)-C(10)-C(15) C(15)-C(10)-C(11)-C(12) C(9)-C(10)-C(11)-C(12) C(10)-C(11)-C(12)-C(13) C(11)-C(12)-C(13)-C(14) C(12)-C(13)-C(14)-C(15) C(13)-C(14)-C(15)-C(10) C(13)-C(14)-C(15)-C(16) C(11)-C(10)-C(15)-C(14) C(9)-C(10)-C(15)-C(14) C(11)-C(10)-C(15)-C(16) C(9)-C(10)-C(15)-C(16) C(14)-C(15)-C(16)-O(8) C(10)-C(15)-C(16)-O(8) C(14)-C(15)-C(16)-O(7) C(10)-C(15)-C(16)-O(7) O(2)-C(1)-O(1)-Li(1) C(2)-C(1)-O(1)-Li(1) O(3)-C(8)-O(4)-Li(2)#1 C(7)-C(8)-O(4)-Li(2)#1 O(6)-C(9)-O(5)-Li(2)#2
Torsion angles 10.57(16) -169.32(12) -168.12(11) 11.99(18) -0.50(17) -179.34(11) 1.1(2) -0.4(2) -0.85(19) 1.43(17) -178.33(11) -0.74(15) 177.90(10) 178.98(10) -2.38(17) -10.79(14) 169.48(11) 167.19(11) -12.54(16) -92.58(14) 82.16(13) 84.65(14) -100.61(14) -0.26(16) 177.13(10) -0.15(18) 0.37(19) -0.19(18) -0.22(16) 178.84(10) 0.44(15) -176.73(10) -178.61(9) 4.22(15) -173.86(10) 5.18(15) 5.71(14) -175.25(9) 108.0(3) -71.9(3) 15.99(18) -161.93(11) -163.77(12)
25 C(10)-C(9)-O(5)-Li(2)#2 O(5)-C(9)-O(6)-Li(1) C(10)-C(9)-O(6)-Li(1) O(7)-C(16)-O(8)-Li(2) C(15)-C(16)-O(8)-Li(2) C(9)-O(6)-Li(1)-O(1) C(9)-O(6)-Li(1)-O(9) C(9)-O(6)-Li(1)-O(10) C(9)-O(6)-Li(1)-Li(1)#3 C(1)-O(1)-Li(1)-O(6) C(1)-O(1)-Li(1)-O(9) C(1)-O(1)-Li(1)-O(10) C(1)-O(1)-Li(1)-Li(1)#3 Li(1)#3-O(10)-Li(1)-O(6) Li(1)#3-O(10)-Li(1)-O(1) Li(1)#3-O(10)-Li(1)-O(9) C(16)-O(8)-Li(2)-O(11) C(16)-O(8)-Li(2)-O(5)#4 C(16)-O(8)-Li(2)-O(4)#5
21.90(18) -37.8(6) 136.5(5) 26.10(19) -154.37(12) -146.2(5) -32.5(6) 97.6(6) 64.9(6) 94.0(3) -25.8(3) -149.8(2) -143.6(2) -62.01(8) 173.73(12) 63.05(10) -162.50(11) 76.79(16) -53.39(19)
Symmetry transformations used to generate equivalent atoms: #1 x+1/2,-y,z+1/2 #2 x,y+1,z #3 -x+1/2,y,-z+1/2 #4 x,y-1,z #5 x-1/2,-y,z-1/2
26 Table 7. Hydrogen bonds for DLDP [Å and deg.]. D-H...A O(4)-H(2)...O(2) O(7)-H(7)...O(3)#5 O(9)-H(9A)...O(5)#3 O(9)-H(9B)...O(2)#2 O(10)-H(10A)...O(5)#4 O(11)-H(11A)...O(2)#3 O(11)-H(11B)...O(9)#3
d(D-H) 1.06(3) 0.864(9) 0.856(9) 0.859(9) 0.843(9) 0.863(9) 0.862(9)
d(H...A) 1.31(3) 1.764(10) 1.859(10) 2.152(11) 2.107(9) 2.311(13) 1.944(11)
d(D...A) 2.3764(13) 2.612(2) 2.7141(15) 2.9906(17) 2.9416(13) 3.1194(17) 2.781(2)
<(DHA) 174(2) 166.8(19) 176(2) 165.4(19) 170.4(18) 156(2) 164(2)
Symmetry transformations used to generate equivalent atoms: #1 x+1/2,-y,z+1/2 #2 x,y+1,z #3 -x+1/2,y,-z+1/2 #4 x,y-1,z #5 x-1/2,-y,z-1/2
Table 8. Tetrahedral Bonds length[Å] and angle [deg] Tetrahedral Bonds
Bond length (Å)
O(1)-Li(1)
1.906(2)
O(6)-Li(1)
1.836(2)
O(9)-Li(1)
1.966(2)
O(10)-Li(1)
2.008(2)
tetrahedra atoms
Bond angle [deg]
O(6)-Li(1)-O(1)
117.22(11)
O(6)-Li(1)-O(9)
110.90(13)
O(1)-Li(1)-O(9)
99.85(10)
O(6)-Li(1)-O(10)
105.11(10)
O(1)-Li(1)-O(10)
105.03(12)
O(9)-Li(1)-O(10)
119.23(10)
27
Table 9: FTIR assignments of DLDP Wavenumber(cm-1)
Assignments
3428
OH-stretching hydrogen bond
2922
OH stretching intermolecule
2852
C-H stretching in ring
1590
Ring structure
1385
C-O stretching
1296
C-C-O asymmetric stretching
1170
OH stretching hydrogen bond overtone
1018
C-O stretching (COOH group)
879
OH overtone
787 630
Four adjacent hydrogen in phase out-ofplane vibration C-O wagging
593
Alkali metal vibration in acid group
465
Out of plane ring bending in meta position
28
Table 10. Nature of fragmentation of DLDP. S.No m/Z 1 397.78
2
355.144
3
207.062
4
167.113
Nature of fragmentation
29 5
122.065
6
104.026
7
77.0965
30
Gr ap hic al ab str act
1. A view of the molecular comlex of Df DLDP is shown above
The vibrational structure of the compound confirms the presence of various functional groups in the molecule. 3. Mass spectrometric analysis provides the molecular weight of the compound and possible ways of 2.
31
fragmentations occurring in the compound. 4. Thermal stability of the crystal was also studied by simultaneous TGA/DTA analyses. 5. The UV-Vis-NIR spectrum was recorded to study the transmittance properties of the grown crystals.
32 HIGHLIGHTS • • •
•
New optical Di-Lithium Di-phthalate single crystals is synthesized. The crystal is a potential candidate for the third order NLO applications. The grown crystals were subjected to X-ray diffraction, FTIR, Mass spectral analysis, Thermo gravimetric and differential thermal analyses and UV-VIS-NIR studies to characterize the crystal. On improving mechanical strength, the crystal can be used in devices.