Crystal structure and spectral properties of vitamin K3 based nitrobenzo[a]phenoxazines

Journal of Molecular Structure 1149 (2017) 84e91

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Journal of Molecular Structure journal homepage: http://www.elsevier.com/locate/molstruc

Crystal structure and spectral properties of vitamin K3 based nitrobenzo[a]phenoxazines Dattatray Chadar a, Debamitra Chakravarty b, Dipali N. Lande a, Shridhar P. Gejji a, Suprabha Sahoo a, Sunita Salunke-Gawali a, * a b

Department of Chemistry, Savitribai Phule Pune University, Pune 411007, India Central Instrumentation Facility, Department of Chemistry, Savitribai Phule Pune University, India

a r t i c l e i n f o

a b s t r a c t

Article history: Received 17 May 2017 Received in revised form 26 July 2017 Accepted 26 July 2017 Available online 27 July 2017

Benzo[a]phenoxazines are the planar polycyclic fluorescent compounds, find a variety of applications in biological sciences and are of growing interest. In the present work we synthesized heterocyclic aromatic fluorescent benzo[a]phenoxazines namely, 6-methyl-9-nitro-5H-benzo[a]phenoxazin-5-one (1) and 6methyl-10-nitro-5H-benzo[a]phenoxazin-5-one (2) which are characterized in terms of the 1H and 13C chemical shifts from 2D gHSQCAD NMR experiments. Single crystal X-ray experiments revealed both 1 and 2 possess the CeH/O interactions. Moreover the p∙∙∙p stacking interactions between planar polycycles have been noticed only in 1. The structural and vibrational spectral inferences obtained from experiments are corroborated through the uB97xD based density functional theory. © 2017 Elsevier B.V. All rights reserved.

Keywords: Vitamin K3 Phenoxazine Benzo[a]phenoxazine Nitro compounds

1. Introduction Phenoxazine and benzo[a]phenoxazine derivatives represent oxygen or nitrogen containing heterocycles having three to five rings which are fluorescent and owing to their high molar absorption coefficient, better photo- [1] and thermostability, thermochromic [2] as well as solvochromic behaviour [3] find applications as metal- [4], pH- [5], gas (H2S)- sensor [6]. The nontoxicity in comparison with other dyes [1] makes them interesting. Moreover the benzo[a]phenoxazine or benzo[a]phenoxazinium salts exhibiting strong fluorescence in the red region of the electromagnetic spectrum (> 600 nm) facilitates their use as long wavelength fluorophores [7,8] and preferred for the biological application [9e14]. The most widely known fluorescent benzo[a]phenoxazine derivatives are Meldola's blue, Nile red, Nile blue [15]. Benzo[a]phenoxazine moieties which serve as fluorescent probes [16e19] or as photosensitizers in (PDT) photodynamic therapy [20,21]. Besides some of benzo[a]phenoxazine derivatives also possess biological activities and widely been used in antituberculosis [22], anti-inflammatory [23] antimalarial [24], antiproliferative [25e27], antitumor [28], antibacterial [29], multidrug

* Corresponding author. E-mail address: [email protected] (S. Salunke-Gawali). http://dx.doi.org/10.1016/j.molstruc.2017.07.091 0022-2860/© 2017 Elsevier B.V. All rights reserved.

resistance activities [30] and to prevent human amyloid disorders [31]. The synthesis and characterization of benzo[a]phenoxazine derivatives from vitamin K3 [32] was carried out earlier in our laboratory. The antiproliferative activity against human breast adenocarcinoma cell line (MCF-7), human carcinoma (HeLa) cell line and normal skin cell line [32] of such derivatives in particular their selectivity toward toxic to malignant cells and not to normal cells [26] motivated us to extend this work with the synthesis and characterization of nitro derivatives of benzo[a]phenoxazine referred hereafter in this report as 1 (6-methyl-9-nitro-5H-benzo [a]phenoxazin-5-one) and 2 (6-methyl-10-nitro-5H-benzo[a]phenoxazin-5-one). 2. Experimental 2.1. General materials and methods Vitamin K3 (2-methyl-1,4-naphthoquinone), 2-amino-4nitrophenol and 2-amino-5-nitrophenol obtained from SigmaAldrich; toluene, methanol and silica-gel with 60e120 mesh size used for column chromatography were procured directly from Merck Chemicals, India. Solvents were distilled using standard procedures [33] and dried wherever necessary. FT-IR spectra were recorded in 4000e400 cm
1 as KBr pellets on

D. Chadar et al. / Journal of Molecular Structure 1149 (2017) 84e91

Scheme 1. Synthesis of benzo[a]phenoxazine from vitamin K3.

SHIMADZU FT 8400 spectrometer which are shown in Fig. S1 to Fig. S3 of ESIy. UVeVisible spectra of compounds on SHIMADZU UV 1650 in DMSO solvent in the range 200e800 nm (displayed in Fig. S4 in ESIy); fluorescence spectra on JASCO spectroflurometer FP-8300 (Fig. S4 in ESIy) and mass spectra were recorded by HR-MS on the Bruker daltonic GmbH (Fig. S5 and Fig. S6 in ESIy). Melting points of all compounds are determined with METTLER which were further corrected using the TA Q2000 differential scanning calorimeter (DSC) (Fig. S7 and Fig. S8 in ESIy). Subsequently 1H, 13C NMR and 2D gHSQCAD in CDCl3 were measured on the Varian mercury 500 MHz NMR using the tetramethylsilane as an internal reference (Fig. S9 and Fig. S10 in ESIy). Elemental analysis was carried out on the Elementar Vario EL III. 2.2. Synthesis of 1 and 2 Vitamin K3 (2-methyl-1,4-naphthoquinone) 5.81 mmol (1 g) was dissolved in 25 ml dry methanol. The solution obtained by dissolution of the 5-nitro aminophenol (0.894 g for 1) and 4-nitro aminophenol (0.894 g for 2) in 15 ml of the dry methanol stirred for 30 min. The amino phenol solutions were added drop wise in the solution of Vitamin K3, and the reaction mixture was refluxed (Scheme 1). The reactions were monitored using thin layer chromatography and the products on plates visualized in the UV chamber. On completion of reaction the reaction mixture was dried

at the room temperature (26  C) for several days. The product(s) thus obtained were dissolved in toluene and purified using column chromatography 9:0.5 (Toluene: Methanol) 5% methanol in toluene which was eluent. A major product that reveals fluorescent orange band was separated. The solvent was reduced by rotatary evaporation and last 20 ml fractions were evaporated at the room temperature (26  C). X-ray quality dark orange colored needle crystals were obtained. 2.3. Characterization of 6-methyl-9-nitro-5H-benzo[a]phenoxazin5-one; 1 Yellow crystal, Yield: 0.40 g (50%), m. p. 264.18  C. Anal. data. Calc. for C17H10N2O4: C, 66.67; H, 3.29; N, 9.15. Found; C, 66.73; H, 3.26, N, 9.35. FT-IR (KBr; nmax (cm
1): 3108, 2921, 1628, 1579, 1525, 1338, 1230, 1096, 962, 828, 522. 1H NMR (500 MHz, CDCl3, d (ppm): 2.26 (s, 3H), 8.70 (1H, d, J ¼ 8.50 Hz, 8.318 (1H, d, J ¼ 8.00 Hz), 8.184 (1H, m, J ¼ 7.00 Hz), 8.174 (1 H, m, J ¼ 7.00 Hz), 7.709 (1 H, s), 7.804 (1 H, d, J ¼ 7.00 Hz), 7.785 (1 H, d, J ¼ 7.00 Hz).13C NMR (125 MHz, CDCl3, d (ppm)): C(1) ¼ 126.63, C(2) ¼ 132.50, C(3) ¼ 133.02, C(4) ¼ 125.31, C(4A) ¼ 132.01, C(5) ¼ 183.61, C(6) ¼ 118.56, C(6A) ¼ 144.62, C(7A) ¼ 137.22, C(8) ¼ 111.93, C(9) ¼ 148.09, C(10) ¼ 120.10, C(11) ¼ 130.19, C(11A) ¼ 150.82, C(12A) ¼ 146.85, C(12B) ¼ 130.58. UVeVis; (lmax (nm), DMSO): 366, 384, 477. Fluorescence (lmax (nm), DMSO): 555. GC-MS (EI) m/z: 306 (MþþH). 2.4. Characterization of 6-methyl-10-nitro-5H-benzo[a] phenoxazin-5-one; 2 Dark yellow crystal, Yield: 0.55 g (80%), m.p. 235.81  C. Anal. data. Calc. for C17H10N2O4: C, 66.67; H, 3.29; N, 9.15. Found; C, 66.76; H, 3.57, N, 9.07. FT-IR (KBr, nmax (cm
1)): 3099, 2958, 2848, 1639, 1599, 1523, 1458, 1338, 1261, 1078, 1024, 968, 896, 833, 734,

Table 1 Crystallographic data of 1 and 2. Identification code

1

2

Empirical formula Formula weight Temperature Wavelength Crystal system Space group Unit cell dimensions

C17 H10 N2 O4 306.27 296(2) K 0.71073 Å Monoclinic C 2/c a ¼ 13.4920(11) Å, b ¼ 15.1908(12) Å, c ¼ 13.6607(15) Å, a ¼ 90 . b ¼ 103.958(3)  . g ¼ 90 . 2717.1(4) Å3 8 1.497 Mg/m3 0.109 mm
1 1264 2.781e28.359 .
18  h<¼17,
20  k<¼20,
18  l<¼18 14209 3369 [R(int) ¼ 0.1063] 99.7% 0.975 and 0.981 Full-matrix least-squares on F2 3369/0/209 0.983 R1 ¼ 0.0714, wR2 ¼ 0.1290 R1 ¼ 0.2088, wR2 ¼ 0.1768 n/a 0.276 and
0.371 e.Å
3

C17 H10 N2 O4 306.27 296(2) K 0.71073 Å Monoclinic P 21/c a ¼ 10.5028(7) Å, b ¼ 15.4190(10) Å c ¼ 8.4959(5) Å a ¼ 90 . b ¼ 101.773(4)  . g ¼ 90 . 1346.91(15) Å3 4 1.510 Mg/m3 0.110 mm
1 632 2.783e28.346 .
13  h<¼14,
19  k<¼20,
11  l<¼11 10299 3316 [R(int) ¼ 0.0569] 99.4% 0.980 and 0.968 Full-matrix least-squares on F2 3316/0/209 1.456 R1 ¼ 0.0654, wR2 ¼ 0.0851 R1 ¼ 0.1731, wR2 ¼ 0.0961 n/a 0.243 and
0.282 e.Å
3

Volume Z Density(calculated) Absorption coefficient F(000) Theta range for data collection Index ranges Reflections collected Independent reflections Completeness to theta ¼ 25.242 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

85

86

D. Chadar et al. / Journal of Molecular Structure 1149 (2017) 84e91

Scheme 2. Reaction pathway accompanying 1 and 2.

694, 642, 534, 488, 432. 1H NMR (500 MHz, CDCl3, d (ppm)): 2.26 (s, 3H), 7.43 (d, 1H), 8.34 (d, 1H), 8.30 (s, 1H), 8.72 (d, 1H), 7.81 (t, 1H), 7.78 (t, 1H), 8.66 (d, 1H). 13C NMR (125 MHz, CDCl3, d (ppm)): C(1) ¼ 126.56, C(2) ¼ 132.70, C(3) ¼ 132.61, C(4) ¼ 126.14, C(4A) ¼ 130.56, C(5) ¼ 183.74, C(6) ¼ 118.53, C(6A) ¼ 146.72, C(7A) ¼ 132.80, C(8) ¼ 116.69, C(9) ¼ 125.39, C(10) ¼ 144.63, C(11) ¼ 130.56, C(11A) 149.12, C(12A) ¼ 149.76, C(12B) ¼ 130.56, C(13) ¼ 8.51. UVeVis; (lmax (nm), DMSO): 328, 365, 440. Fluorescence (lmax (nm), DMSO): 560. GC-MS (EI) m/z: 306 (MþþH). Fig. 1. ORTEP of 1 and 2.

2.5. X-ray crystallographic data collection and refinement of the structures for 1 and 2 The crystals were grown in toluene. Orange needle shaped crystal of dimensions 0.37  0.26  0.21 mm was selected for X-ray diffraction analysis. Data for the compound has been collected on D8 Venture PHOTON 100 CMOS diffractometer using graphite monochromatized Mo-Ka radiation (l ¼ 0.7107 Å) with exposure/ frame ¼ 10s. The X-ray generator was operated at 50 kV and 30 mA. An initial set of cell constants and an orientation matrix were calculated from total 24 frames. The optimized strategy used for data collection consisted different sets of f and u scans with 0.5 steps in f/u. Crystal to detector distance was 5.00 cm with 512  512 pixels/frame, Oscillation/frame
0.5 , maximum detector swing angle ¼
30.0 , beam centre ¼ (260.2, 252.5), in plane spot width ¼ 1.24. Data integration was carried out by Bruker SAINT Program and empirical absorption correction for intensity data

were incorporated through Bruker SADABS. The programs are integrated in APEX II package [34]. The data were corrected for the Lorentz and polarization effects. Further the structure was solved by the direct Method using SHELX-97 [35] the finally refined by employing the full-matrix least-squares techniques using anisotropic thermal data for the non-hydrogen atoms on F2. The nonhydrogen atoms were refined anisotropically whereas the hydrogen atoms were refined at calculated positions as riding atoms with the isotropic displacement parameters [35]. Finally the structures are obtained through the ORTEP-3 [36] and Mercury software programs [37]. The final structures were derived by using SHELXTL [38] and PLATON [39]. CCDC number for 1 is 1479791 and 2 is 1494130. Crystallographic data is presented in Table 1. 2.6. Computational details Optimization of 1 and 2 structures were carried out using the

uB97x-D hybrid density functional theory employing the Gaussian

Table 2 1 H NMR chemical shifts in 1 and 2. 1

H1 H2 H3 H4 H8 H9 H10 H11 H13

2

Theo.

Expt.

Theo.

Expt.

9.95 8.53 8.57 10.00 9.11 e 9.57 8.72 2.55

8.70 8.18 8.17 8.31 7.70 e 7.80 7.78 2.26

9.93 8.93 9.00 8.60 8.39 8.97 e 9.60 2.55

8.66 7.81 7.78 8.72 7.43 8.34 e 8.30 2.26

Table 3 Hydrogen bond geometries for 1 and 2. D-H∙∙∙A 1

2

(i)

C(1)eH(1)∙∙∙O(5) C(2)eH(2)∙∙∙O(13B) (ii) C(10)eH(10)∙∙∙O(13A)(iii) C(2)eH(2)∙∙∙O(5) (v) C(9)eH(9)∙∙∙O(13B) (iv)

D-H(Ǻ)

H∙∙∙A(Ǻ)

D∙∙∙A(Ǻ)

:D-H∙∙∙A( )

0.930 0.930 0.930 0.931(2) 0.930(2)

2.548 2.687 2.409 2.573 2.413

3.273(3) 3.469(3) 3.261(3) 3.375(3) 3.298(3)

135.1 142.2 152.2 144.7 159.0

(i) 1/2-x,-1/2 þ y,1.5-z; (ii),
1þx,-y,-1/2 þ z; (iii),
1/2-x,-1/2-y,1-z; (iv)
1/2 þ y,1/2-z; (v) 2-x,-y,2-z.

D. Chadar et al. / Journal of Molecular Structure 1149 (2017) 84e91

87

Fig. 2. CeH/O and p∙∙∙p interactions in 1.

Fig. 5. CeH/O interactions of three 2 molecules.

dependent Density Functional Theory (TD-DFT) was used to assign the electronic transitions in the UVevisible spectra. Frontier orbitals were visualized subsequently. X-ray crystal structure data on the 1 and 2 were subjected to Crystal explorer-3.1 programs. Subsequently the charge distribution was characterized in terms of the Hirshfeld surfaces. Lastly 1H NMR chemical shifts (d, in ppm) were derived by subtracting the nuclear magnetic shielding tensors of protons in 1 or 2 from those in the tetramethylsilane (TMS) which was the reference within the framework of the gauge invariant atomic orbital (GIAO) method. 3. Results and discussion

Fig. 3. Planar sheets (consisting seven molecules) of 1 formed via CeH/O interaction.

Synthesis of 1 and 2 and their characterization employing a variety of experimental tools such as 1H and 13C NMR, UVeVisible,

09 program [39] in conjunction with the internally stored 6311þþG(d,p) basis set. Stationary point structures on the multivariate potential energy surfaces thus obtained were confirmed to be local minima through the vibrational frequency calculations since all the normal vibration frequencies turned out to be real; the harmonic vibration frequencies obtained were scaled by 0.92. Time

Fig. 4. Molecular packing in 1 viewed down b axis showing CeH/O hydrogen bonding and p∙∙∙p stacking.

Fig. 6. CeH/O interaction leading to hexagon arrangements as in 2.

88

D. Chadar et al. / Journal of Molecular Structure 1149 (2017) 84e91

Fig. 7. Hirshfeld surfaces mapped with (a) dnorm (b) shape index, (c) curvedness and (d) 2D finger print plots in 1 and 2.

FT-IR combined with the DFT based theory have been outlined in the following. 3.1. Synthesis of 1 and 2 Benzo[a]phenoxazine derivatives 1 and 2 were synthesized by condensation of Vitamin K3 (a) with 2-amino-5-nitrophenol for 1 and 2-amino-4-nitrophenol for 2 (b) are refluxed in methanol (Scheme 1). Unsymmetrical Michael acceptor molecule Vitamin

K3 (a) (Scheme 2) abstract acidic phenolic proton and generate oxonium ion (c) and phenolate anion (d). Phenolate ion reacts on b position of oxonium ion to form enol (e). Enol (e) moiety converts to ketone by keto-enol tautomerism (f). Other nucleophilic amino moiety reacted via 1,2-addition leading to aminol intermediate (g) as an unstable moiety, which immediately loses the water molecule yielding stable imino species, which aromatizes via oxidation engendering benzo[a]phenoxazine derivatives (i).

D. Chadar et al. / Journal of Molecular Structure 1149 (2017) 84e91

89

Fig. 8. Optimized structures of 1 and 2 from ub97x-D theory.

3.2. FT-IR, UVevisible, fluorescence, 1H and

13

respectively.

C NMR studies

As depicted in Fig. S1 (ESI) the infrared spectra shows the carbonyl stretching of the parent Vitamin K3 near 1669 cm
1, which shifts to lower wavenumber ~1628 cm
1 in 1. Besides the ~1639 cm
1 band of 2 is observed to shift by 14 cm
1 on either side as compared to those in benzo[a]phenoxazine derivatives reported earlier [25,27,32]. These shifts further can be explained from the electron withdrawing nature of the NO2 substituent [40e42]. A broad band near ~1590 ± 5 cm
1 was assigned to C]N stretching. The paranaphthoquinone (p-NQ) vibration [10] in quinonoid ring (~1260 cm
1) was not noticed in both 1 and 2 as well. The carbonyl stretching in these two systems assigned to ~1230 cm
1 and 1224 cm
1 vibration, respectively. UVeVisible spectra of vitamin K3 in DMSO displayed two bands ~266 nm and ~330 nm. The ~330 nm (of vitamin K3) band shifted to ~ 360 nm in the 1 which compares well with the corresponding 365 nm band as observed in the spectra. Moreover the 477 nm band was observed in 1 that corresponds to 440 nm band in 2. Further the fluorescence emission band occurs in 450e700 nm. It is discernible here that the enhanced fluorescent intensity was noticed in 1 than 2 for the same concentrations in the measured spectra. 1 H and 13C NMR spectra measured in CDCl3 solution (Table 2) showed that CH3 protons led to up-field signals in 1H NMR observed near d ¼ 2.26 ppm in 1 and 2. Likewise two doublets for (CeH1) and (CeH4) were noticed. (CeH2, 3) of benzenoid ring shows 2H multiplets in the spectra. Moreover (CeH1) and (CeH4) protons (cf. Scheme 1) of benzenoid ring ‘A’ engender down-field chemical shifts d ¼ 8.70 ± 0.4 ppm. The carbonyl carbon 5 (C]O) in 13C NMR spectrum displayed at the d ¼ 183.61 ppm in 1 and 2 whereas the imine carbon (12A) (C]N) emerge with its signal near d ¼ 146.85 ppm in 1 which compares well with d ¼ 149.76 ppm for 2, Table 4 Selected bond distances of (optimized and experimental) 1 and 2. Bond

C(5) ¼ O(5) C(12A)-N(12) C(8)eH(8) CeN(13) C(11)eH(11)

1

2

Theo.

Expt.

Theo.

Expt.

1.2162 1.2867 1.0813 1.4760 1.0829

1.226 1.295 0.930 1.466 0.930

1.2164 1.2854 1.0825 1.4720 1.0817

1.234 1.293 0.930 1.476 0.930

3.3. Single crystal X-ray diffraction analysis Compound 1 crystallizes in monoclinic space group C2/c and ORTEP plot as shown in Fig. 1. The carbonyl bond distances C(5) ¼ O(5) are close to those of the oxidized form of naphthoquinone or other menadione analogues [43,44]. Compound 1 is surrounded with five neighbouring molecules held together by CeH/O interaction (Table 3) and other two molecules, one above the (C(1)∙∙∙C(8), 3.395(4) Å,
1/2-x,1/2-y, 1-z) and other below (C(11A)∙∙∙C(11A), 3.386(4) Å, (
1/2-x,1/2-y, 1-z) the plane of 1 (Fig. 2) via p-p stacking interactions facilitated via nitro group (O(13A) and O(13B)) and the quinonoid oxygen O(5). Such interactions engender the planar polymeric sheet. The CeH/O interactions are displayed in Fig. 3. The p∙∙∙p stacking interactions in 1 are noticed on viewing down the b-axis as depicted in Fig. 4. Compound 2 crystallizes in the monoclinic space group P21/C and ORTEP plot as shown in Fig. 1. Crystal structure of 2 reveals three molecules bound via CeH/O interactions facilitated by one of the nitro oxygen O(13)B as shown in Fig. 5. A reverse orientation of molecules brings forth O(13B)/H(9) interactions between two NO2 groups leading to a hexagonal arrangements as displayed in Fig. 6. 3.4. Hirshfeld surfaces of 1 and 2 Hirshfeld surfaces refer to molecules in molecular crystals and

Table 5 Experimental and optimized vibrational frequencies (n in cm
1) of 1 and 2. 1

n(C(1)eH(1)) n(C(4)eH(4)) n(C(8)eH(8)) n(C(9)eH(9)) n(C(10)H(10)) n(C(11)H(11)) n(CH3) n(C]O) n(C(6) ¼ C(6A)) n(NO)2

2

Theo.

Expt.

Theo.

Expt.

2994 2989 2999

3245 3203 3115

2992 2985 3008

2956 e 3102 3257

3007 2835e2838 1632 1604 1331

3163 3068e2965 1639 1600 1454

3012 2827e2930 1634 1600 1329

3111e2857 1628 1579 1453

90

D. Chadar et al. / Journal of Molecular Structure 1149 (2017) 84e91

Fig. 9. Frontier molecular orbitals in (a) 1 and (b) 2.

enrich the explanation and rationalization of structural motifs which can be derived using the Crystal Explorer 3.1. The graphical 2D-fingerprint plots were constructed by plotting the distance external to the Hirshfeld surface (de) against the distance internal to the surface (di). (cf. Fig. 7). Fingerprint plots (and Hirshfeld surfaces) thus derived are distinctive for any crystal structure and subsequently for any polymorph and have emerged as a powerful tool for interpreting as well as comparing intermolecular interactions. The common features/trends in specific classes of compounds can thus be identified. Fig. 7 displays surfaces mapped with dnorm, shape index, curvedness and finger print plot in 1 and 2 as well. A direct visual comparison impart a intense red color around a O(13A) and H(1) functionality for 1 studied herein contribute more toward CeH/O interactions. On the other hand, in case of 2 intense red spots observed around O(13B) and H(9), suggest the underlying molecular interactions are qualitatively different. Moreover specific packing modes and the ways in which the nearby molecules contact one another can be identified through shape index or curvedness parameters. For all molecules a shape index revealed the red concave region on surface around the oxygen atoms and aromatic p cloud rendered located near the hydrogen atoms was imparted with the blue. Moreover the p∙∙∙p stacking interactions in menadione derivatives as also evidenced from the adjacent red and blue triangles pattern appearing on the shape index surfaces. A large and flat green region on the same side of the molecule on the corresponding curvedness surfaces was observed. The CeH/O and p∙∙∙p stacking can thus be segregated

from such fingerprint plots. 3.5. DFT investigations Optimized structures of 1 and 2 menadione derivatives obtained from the uB97x-D density functional theory have been displayed in Fig. 8. Selected bond distances and angles are compared with those from the X-ray crystal data in Table 4. As may readily be noticed the structural parameters compare well with the experiment. Substitution of the NO2 group at C(10) position led to C(5)O(5) bond to be 0.02 Å longer. Structural ramifications and underlying molecular interactions are further probed through the normal vibration analysis. Calculated vibrational spectra are compared with the experiment in Table 5. As is evident the carbonyl stretching vibrations located at 1634 and 1632 cm
1 in 1 and 2, respectively. Secondly the NO2 stretching at 1329 cm
1 in 1 corresponds to 1331 cm
1 vibration in 2. 1 H NMR chemical shifts (dH) in 1 and 2 in CDCl3 (as solvent) simulated through the SCRF-PCM theory are compared with the experiment in Table 2. As shown the H(4) proton of 1 participating in the intramolecular CeH/O interactions emerges with the relatively large deshielding with a signal near 10.0 ppm whereas the corresponding signal was noticed at 8.60 ppm in 2. Further methylene protons show up-field dH signals in the calculated spectra. These inferences on dH parameters concur with the experiment. In an effort to understand the electronic properties at the molecular level the electronic transitions were assigned using the

D. Chadar et al. / Journal of Molecular Structure 1149 (2017) 84e91

time-dependent DFT (TD-DFT). A plot of the most representative molecular frontier orbitals in the ground state are illustrated in Fig. 9. In both these isomers the HOMOs are rendered with relatively large p character and reside on aromatic moieties. The double bond(s) in 1 and 2 show absorption maxima for HOMO to LUMO transitions near 404 nm and 379 nm, respectively.

[8] [9] [10] [11] [12] [13]

4. Conclusions Fluorescent nitro benzo[a]phenoxazine derivatives 1 and 2 were synthesized from Vitamin K3 and nitro aminophenol and characterized by different analytical tools. Reaction scheme for synthesis of 1 and 2 have been given. Single crystal X-ray data display five and three neighbouring molecules in 1 and 2 are held together via the CeH/O intermolecular hydrogen bonding. In addition to this the p∙∙∙p stacking interactions in 1 are evident. A planar polycycles in 2 engenders CeH/O hydrogen bonding subsequently leading to the hexagon-like arrangements. The position of the eNO2 substituent reveals its signature in the carbonyl vibrations. The 13C NMR signals of the imine carbon C(12A) in 1 and 2 appear near 147 ppm and 150 ppm, respectively. Calculated 1H NMR and the vibrational frequencies from theory are in consonance with the experiment. Acknowledgements SSG grateful to RGYI scheme of Department of Biotechnology, New Delhi, India for Ref. No. (BT/PR6565/GBD/27/456/2012. SPG acknowledges support from the Research Project (37(2)/14/11/ 2015-BRNS) from the Board of Research in Nuclear Sciences, India. DC thankful to Union Grants Commission, New Delhi, India for senior research fellowship. DNL and SS thankful to Savitribai Phule Pune University for the award of research fellowship through the University of Potential excellence scheme from the University Grants Commission, New Delhi, India. SPG thanks Centre for Development of Advanced Computing (C-DAC), Pune for computer time on National Param Supercomputing Facility.

[14] [15] [16] [17] [18] [19] [20] [21] [22]

[23] [24]

[25]

[26] [27] [28] [29] [30] [31] [32] [33]

Appendix A. Supplementary data

[34]

Supplementary data related to this article can be found at http:// dx.doi.org/10.1016/j.molstruc.2017.07.091.

[35] [36] [37]

References [1] B.R. Raju, A.M.F. Garcia, A.L.S. Costa, P.J.G. Coutinho, M.S.T. Gonçalves, Dyes Pigments 110 (2014) 203. [2] C.M. Golini, B.W. Williams, J.B. Foresman, J. Fluoresc. 8 (1998) 395e404. [3] C. Reichardt, Chem. Rev. 94 (1994) 2319e2358. [4] M.M. Hu, J.H. Yin, Y.H. Li, X.F. Zhao, J. Fluoresc. 25 (2015) 403e408. [5] J. Madsen, I. Canton, N.J. Warren, E. Themistou, A. Blanazs, B. Ustbas, X. Tian, R. Pearson, G. Battaglia, A.L. Lewis, J. Am. Chem. Soc. 135 (2013) 14863e14870. [6] X.-D. Liu, C. Fan, R. Sun, Y.-J. Xu, J.-F. Ge, Anal. Bioanal. Chem. 406 (2014) 7059e7070. [7] B.R. Raju, A. Daniela, G. Firmino, A.L.S. Costa, P.J.G. Coutinho, M.S.T. Gonçalves,

[38] [39]

[40] [41] [42] [43] [44]

91

Tetrahedron 69 (2013) 2451e3246. L. Yuan, W.K. Zheng, L. He, W. Huang, Chem. Soc. Rev. 42 (2013) 622e661. A.D.G. Firmino, M.S.T. Gonçalves, Tetrahedron Lett. 53 (2012) 4946e4950. J. Xu, S. Sun, Q. Li, Y. Yue, Y. Li, S. Shao, Analyst 140 (2015) 574e581. K. Tanabe, Z. Zhang, T. Ito, H. Hatta, S.-I. Nishimoto, Org. Biomol. Chem. 5 (2007) 3745e3757. M. Liu, M. Hu, Q. Jiang, Z. Lu, Y. Huang, Y. Tan, Q. Jiang, RSC Adv 5 (2015) 15778e15783. R. Sun, W. Liu, Y.-J. Xu, J.-M. Lu, J.-F. Ge, M. Ihara, Chem. Commun. 49 (2013) 10709e10711. S.S. Bag, S. Ghorai, S. Jana, RSC Adv. 3 (2013) 5374e5377. J. Jose, K. Burgess, Tetrahedron 62 (2006) 11021e11037. T. Terai, T. Nagano, Pflugers Arch. 465 (2013) 347e359. W. Liu, R. Sun, J.F. Ge, Y.J. Xu, Y. Xu, J.M. Lu, I. Itoh, M. Ihara, Anal. Chem. 85 (2013) 7419e7425. E. Oliveira, C.I.M. Santos, H.M. Santos, A. Fernandez-Lodeiro, Dyes Pigments 110 (2014) 219e226. J. Zhang, A. Shibata, M. Ito, S. Shuto, Y. Ito, B. Mannervik, H. Abe, R. Morgenstern, J. Am. Chem. Soc. 133 (2011) 14109e14119. K. Hirakawa, K. Ota, J. Hirayama, S. Oikawa, S. Kawanishi, Chem. Res. Toxicol. 27 (2014) 649e655. M. Lopes, C.T. Alves, B.R. Raju, M.S.T. Gonçalves, P.J.G. Coutinho, M. Henriques, I. Belo, J. Photochem. Photobiol. 114 (2014) 93e99. F. Paula Carneiro, M.D. Carmo, F.R. Pinto, S.T. Coelho, B.C. Cavalcanti, C. Pessoa, C.A.D. Simone, I.K.C. Nunes, N.M.D. Oliveira, R.T.D. Almeida, A.V. Pinto, K.C.D.G. Moura, K.D. Moura, P.A.D. Silva, E.N.D. Silva Jr., Eur. J. Med. Chem. 46 (2011) 4521e4529. B. Blank, L.L. Baxter, J. Med. Chem. 11 (1968) 807e811. J.-F. Ge, Chika Arai, M. Yang, A. BakarMd, J. Lu, N.S.M. Ismail, S. Wittlin, M. Kaiser, R. Brun, S.A. Charman, T. Nguyen, J. Morizzi, I. Itoh, M. Ihara, ACS Med. Chem. Lett. 1 (2010) 360e364. L. Kathawate, P.V. Joshi, T.K. Dash, S. Pal, M. Nikalje, T. Weyhermüller, V.G. Puranik, V.B. Konkimalla, S. Salunke-Gawali, J. Mol. Struct. 1075 (2014) 397e405. S. Pal, V.B. Konkimalla, S. Salunke-Gawali, Anti-Cancer Agents Med. Chem. 17 (1) (2017) 115e125. S. Pal, V.B. Konkimalla, L. Kathawate, S.S. Rao, S.P. Gejji, V.G. Puranik, T. Weyhermüller, S. Salunke-Gawali, RSC Adv. 5 (2015) 82549e82563. K. Hara, M. Okamoto, T. Aki, H. Yagita, H. Tanaka, Y. Mizukami, H. Nakamura, A. Tomoda, N. Hamasakiand, D. Kang, Mol. Cancer Ther. 4 (2005) 1121e1127. K. Desai, A.J. Baxi, J. Ind. Chem. Soc. 69 (1992) 212e217. O. Wesolowaska, J. Molnar, G. Westman, K. Samuelsson, M. Kawase, I. Ocsovszki, N. Motohashi, K. Michalak, Vivo 20 (2006) 109e114. T. Klabunde, H.M. Petrassi, V.B. Oza, P. Raman, J.W. Kelly, J.C. Sachhettini, Nat. Struct. Biol. 7 (2000) 312e321. D. Chadar, S.S. Rao, A. Khan, S.P. Gejji, K.S. Bhat, T. Weyhermüller, S. SalunkeGawali, RSC Adv. 5 (2015) 57917e57929. D.D. Perrin, W.L. Armarego, D.R. Perrin, Purification of Laboratory Chemicals, Pergamon Press, London, 1988, p. 260. Bruker, APEX2, SAINT and SADABS, Bruker AXS Inc, Madison, Wisconsin, USA, 2007. G.M. Sheldrick, ActaCryst A64 (2008) 112e122. L.J. Farrugia, J. Appl. Cryst. 45 (2012) 849e854. C.F. Macrae, I.J. Bruno, J.A. Chisholm, P.R. Edgington, P. McCabe, E. Pidcock, L.R. Monge, R. Taylor, J. van de Streek, P.A. Wood, J. Appl. Crystallogr. 41 (2008) 466e470. L. Spek, ActaCryst D65 (2009) 148e155. M.J. Frisch, G.W.Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, G.Scalmani, V. Barone, B.Mennucci, G.A.Petersson, et al. Gaussian, Inc., Wallingford CT (2009). €fer, J. Org. Chem. 45 (1980) 2155e2161. N.L. Agrawal, W. Scha €fer, J. Org. Chem. 45 (1980) 5141e5143. N.L. Agrawal, W. Scha €fer, J. Org. Chem. 45 (1980) 5144e5149. N.L. Agrawal, W. Scha D. Chadar, M. Camilles, R. Patil, A. Khan, T. Weyhermüller, S. Salunke-Gawali, J. Mol. Struct. 1086 (2015) 179e189. A. Patil, D.N. Lande, A. Nalkar, S.P. Gejji, D. Chakrovorty, R. Gonnade, T. Moniz, M. Rangel, E. Periera, S. Salunke-Gawali, J. Mol. Struct. 1143 (2017) 495e514.