Vibrational spectroscopic analysis of aluminum phthalocyanine chloride. experimental and DFT study

Author’s Accepted Manuscript Vibrational Spectroscopic analysis of aluminum phthalocyanine chloride. experimental and DFT study I.M. Soliman, M.M. El-Nahass, Kh.M. Eid, H.Y. Ammar www.elsevier.com/locate/physb

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S0921-4526(16)30093-X http://dx.doi.org/10.1016/j.physb.2016.03.023 PHYSB309410

To appear in: Physica B: Physics of Condensed Matter Received date: 23 December 2015 Revised date: 12 March 2016 Accepted date: 14 March 2016 Cite this article as: I.M. Soliman, M.M. El-Nahass, Kh.M. Eid and H.Y. Ammar, Vibrational Spectroscopic analysis of aluminum phthalocyanine chloride. experimental and DFT study, Physica B: Physics of Condensed Matter, http://dx.doi.org/10.1016/j.physb.2016.03.023 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Vibrational Spectroscopic Analysis of Aluminum Phthalocyanine Chloride. Experimental and DFT Study I.M. Soliman a,*, M.M. El-Nahass b, Kh.M. Eid b, H.Y. Ammar c a b

Physics Department, Faculty of Science, Ain Shams University, Abbasia, Cairo, Egypt Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt c Physics Department, Faculty of Arts and science, Najran University, Najran, Saudi Arabia

Abstract: In this work, we report a combined experimental and theoretical study of aluminum phthalocyanine chloride (AlPcCl). The FT-IR and Raman spectra of AlPcCl were recorded and analyzed. The density functional theory (DFT) computations have been performed at B3LYP/6-31g and B3LYP/6-311g to derive equilibrium geometry, vibrational wavenumbers, intensity and NLO properties. All the observed vibrational bands have been discussed and assigned to normal mode or to combinations on the basis of our DFT calculations as a primary source of attribution and also by comparison with the previous results for similar compounds. The natural bond orbital (NBO) calculations were performed to study the atomic charge distribution of the investigated compound. The calculated results showed that dipole moment of the investigated compound was 4.68 Debye and HOMO-LUMO energy gap was 2.14 eV. The lowering of frontier orbital gap appears to be the cause of its enhanced charge transfer interaction. *Corresponding author: [email protected] Keywords: FT-IR; HF; DFT; vibrational analysis; HOMO-LUMO energies.

1. Introduction Organic semiconducting materials are of particular interest, since they possess prosperous optoelectronic, electrical and processing properties for designing and fabrication of electronic devices [1]. Among these materials, a series of phthalocyanines represent a large family of heterocyclic conjugated molecules with high chemical stability. Phthalocyanines as a class of organic materials are 1

generally thermally stable and can easily be deposited as thin films with high quality by thermal evaporation without dissociation. Metal phthalocyanines (MPc’s) have gained considerable attention in recent years because they have been successfully applied in many applications such as gas sensors [2, 3], solar cells [4– 6] and light emitting diodes [7, 8]. Optical absorption studies of MPc’s thin films have attracted the researchers over the last few years [9, 10]. Relatively few studies have focused on the halogenated MPc’s although there is evidence that they may exhibit properties suitable for gas sensing applications [11]. It has also been shown that the halogenated Pc’s exhibit remarkable morphological and thermal stability over a larger temperature range compared to unhalogenated Pc’s [12]. One of the most halogenated MPc’s derivatives is aluminum phthalocyanine chloride (AlPcCl) which is the focus of our study. It has a chemical formula of (C32H16AlClN8). One of the effective tools which have been used to simulate vibrational analysis of complex molecules is the quantum chemical calculations. In the present work, we introduce a combined computational and experimental investigation for the optimized molecular structural parameters, vibrational spectra, total dipole moment, thermo-chemical parameters and HOMO-LUMO energy gap of the investigated compound using density functional theory DFT/B3LYP utilizing 6-311G basis set. 2. Material and method 2.1. Experimental details The AlPcCl powder (C32H16AlClN8) was obtained from Sigma- Aldrich Chem. Co. and used as received. Infrared spectroscopy of AlPcCl in powder and thin film forms was performed using ATI Mattson (Infinity series FTIR) infrared spectrophotometer in the spectral range 4000–400 cm-1. A good signal-to-noise ratio was obtained from the accumulation of 128 scans with spectral resolution of 4.0 cm-1. The Fourier transform Raman (FT-Raman) spectrum of the same compound was recorded using a Perkin-Elmer FT-Raman spectrometer. The incident laser excitation is 632 nm. The scattered light was collected at the angle of

in the region 3600–50 cm -1 and the resolution was set up to 2 cm -1.

2.2. Computational details Fully optimized ground state geometry and harmonic vibrational wavenumbers of AlPcCl were calculated using the Gaussian 09W [13] software package, and Gauss View 5.0 molecular visualization program Package [14].

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A geometrical optimization without any constraint of the investigated compound was done HF and B3LYP utilizing 6-31G and 6-311G basis set for C, N, Al, Cl and H atoms. The resultant-optimized geometry at DFT/B3LYP utilizing 6-311G basis set is shown in Fig. 1. Resultant-optimized geometries were used as inputs for vibrational frequencies calculations at DFT/B3LYP to characterize all stationary points as minima. DFT method, including local or non-local functionals, yields molecular force fields and vibrational wavenumbers in comparable agreement with experimental results. We have selected the B3-LYP [15] among the many available DFT methods, which combines Becke’s three-parameter exchange functional (B3) with the Lee, Young and Parr correlation functional (LYP). Natural bond orbital (NBO) calculations of AlPcCl were performed at the B3LYP/6-311G level using the program NBO 3.1 [16] included in the Gaussian 09W package. 3. Results and discussion 3.1. Optimized molecular geometry Computational values of bond lengths and bond angles for the investigated structure are listed in Table S1 in accordance with atom numbering scheme as shown in Fig. 1. For example: R(1,2), R(1,3) R(3,9), R(3,10), R(9,57) and R(57,58) have bond lengths of 1.390, 1.452, 1.403, 1.291, 1.985 and 2.285 Å calculated at HF/6-31G, 1.395, 1.458, 1.405, 1.292, 1.985 and 2.258 Å calculated at HF/6-311G, 1.412, 1.455, 1.405, 1.336, 2 and 2.276 Å calculated at B3LYP/6-31G and 1.412, 1.455, 1.402, 1.336, 1.996 and 2.253 Å calculated at B3LYP/6-31G, respectively. Also, A(2,1,3), A(2,1,55), A(4,2,49), A(9,3,10), A(3,9,57), A(9,57,12) and A(9,57,58) have bond angles of 106.7, 121, 131.7, 126.6, 124.8, 88.2 and 101.7° calculated at HF/6-31G, 106.7, 121, 131.7, 126.6, 124.8, 88.3 and 101.7° calculated at HF/6-311G, 106.7, 121.2, 132, 127, 125, 87.4 and 102.1° calculated at B3LYP/6-31G and 106.7, 121.1, 132, 126.9, 125.9, 87.5 and 102° calculated at B3LYP/6-311G, respectively. One can observe that the geometrical optimization more sensitive to the method of calculation (HF or B3LYP) than the utilized bases set (6-31G or 6-311G). The aluminum sites are above (about 0.41 Å) the plane of the ring. From our calculated structural parameters, we found that the B3LYP/6-311G is more accurate in predicting the experimental ones.

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3.2. Infrared spectra The investigated compound (C32H16AlClN8) has 58 atoms and 168 vibrational modes which possess C1 symmetry. We select only 21 modes of our calculated modes of vibrations, which fit with our experimental assignments collected in Table 1. Vibrational spectral assignments have been performed on the recorded FT-IR spectrum, are based on the computationally predicted wavenumbers by B3LYP/6-311G. All the calculated modes are numbered from the largest to the smallest frequency within each fundamental wavenumber. The calculated and scaled vibrational wavenumbers are collected also in Table 1 with the scaling factor 0.96 [15] for B3LYP level. All the 21 fundamental vibrations are active. Fig. 2 shows the calculated IR spectrum at B3LYP/6-31G and B3LYP/6-311G with experimental FT-IR spectra of bulk form and thin film. Although the molecular structure Fig. 1 does not contain hydroxyl group, there is a broad band appear at 3461 cm-1 for bulk form and 3232 cm-1 for thin film form in our experimental FT-IR spectra Fig. 2 (a and b) which corresponds to O-H stretching vibration. The presence of the hydroxyl group O-H despite the molecular structure does not contain this group indicates that our investigated material absorbs water from its surrounding atmosphere, our theoretical calculations confirmed this interpretation, due to the absence of the vibrational mode corresponding to O-H group. Comparison of the vibrational frequencies calculated at B3LYP/6-311G with experimental values (see Table 1) reveals that B3LYP/6-311G basis set gives reasonable deviations from the experimental values. C–H Vibrations The aromatic C-H stretching vibrations are expected to appear in the spectral range 3000–3100 cm−1 [17]. The computed vibration (mode 1) is assigned to aromatic C-H symmetric stretching vibration at 3050.17 cm-1 which is comparable to experimental data at 3054 cm-1 for bulk form. The computed vibrations (modes 6 and 7) are assigned to C-H in-plane bending vibration at 1292 and 1165 which are comparable to experimental data at 1290 and 1166 cm-1 for bulk form, 1290 and 1166 cm-1 for thin film, respectively. The C-H out-of-plane bending vibration is generally observed in the spectral range 667–900 cm−1 [17, 18]. The computed vibration (mode 10) is assigned to C-H out of plan bending vibrations at 965. cm-1 which is comparable to our experimental data at 952 cm-1 for bulk form. The computed vibrations 4

(modes 11, 13 and 14) are assigned to C-H out of plan bending vibrations at 882, 746 and 731 cm-1 which are comparable to our experimental data at 904, 763 and 728 cm-1 for bulk form, 898, 757 and 730 cm-1 for thin film form, respectively. C=C Vibrations In aromatic compounds the ring C=C stretching vibrations appear in general at the spectral range 1480–1630 cm−1 [19]. The computed vibration (mode 2) is assigned to C=C stretching vibration at 1588 cm−1 which is comparable to our experimental data at 1585 cm-1 for thin film form. The computed vibration (mode 5) is assigned to C=C stretching vibration at 1324 cm−1 which is comparable to experimental data at 1332 cm-1 for bulk form and 1334 cm-1 for thin film. C=N Vibrations The computed vibrations (modes 3 and 4) are assigned to C=N stretching vibrations at 1490 and 1459 which are comparable to our experimental data at 1496 and 1465 cm-1 for bulk form, 1496 and 1457 cm-1 for thin film form, respectively. Al-Cl Vibrations The computed vibrations (modes 19 and 20) are assigned to Al-Cl stretching vibration at 461 and 436 cm−1. Which are comparable to our experimental data at 468 and 431 for thin film, respectively. Isoindole vibrations The computed vibrations (modes 9, 15-18 ) are assigned to isoindole skeletal vibrations at 1061 , 666, 643, 583 and 510 cm−1 which are comparable to our experimental data at 1066, 644, 617, 568 and 512 cm-1 for bulk form, 1066, 661, 615, 559 and 516 cm-1 for thin film form, respectively. The computed vibrations (modes 12 and 21) are assigned to isoindole deformation vibrations at 815 and 415.7 cm−1 which are comparable to our experimental data at 819 and 414 cm-1 for bulk form, respectively. 3.3. Raman spectra Theoretical Raman vibrational frequencies of AlPcCl were calculated using B3LYP/6-311G basis set and were compared with the experimental results as shown in Fig. 3. As shown most of the vibrational modes appear among 1700–400 cm-1. The peaks appear above 3000 cm-1 in the calculated data is due to C–H stretching, this is similar to other theoretical studies of metal phthalocyanine [20]. A linear fitting 5

function was applied to the calculated frequencies to improve the correlation with experimental data, as shown in Fig.4. The slope of the line is 0.999 and the intercept is 2.57 cm-1, which shows good consistency between experimental and calculated data. 3.4. Other molecular properties We insert in Table 2 several calculated thermodynamic parameters such as total energy, zero-point vibrational energy (ZPVE) and rotational constants. The ability of the studied molecule to interact with the surrounding environment can be detected through total dipole moment [21]. The dipole moment of the investigated compound is 4.68 Debye which indicates high reactivity to interact with the surrounding media. The natural bond orbital (NBO) calculations were performed using NBO 3.1 program implemented in Gaussian 09W package at B3LYP/6-311G level in order to study the atomic charge distribution of investigated compound. The charge distribution of aluminum phthalocyanine chloride Fig. 5 shows that C3, C4, C7, C8, C16, C17, C22 and C23 atoms have a positive charge of 0.437 au whereas the rest of carbon atoms have a negative charge, these carbon atoms are attached directly to the negatively charged nitrogen atoms, shows a charge transfer from carbon atoms to nitrogen atoms. The nitrogen atoms N9, N12, N18 and N24, which attached directly to the Al atom, have a more negative charge (-0.727 au) than the rest nitrogen atoms (-0.472 au) shows a charge transfer from the Al atom to N9, N12, N18 and N24 atoms. Also the negative charge on the Cl atom (-0.552 au) shows a charge transfer from the positively charged Al atom to the Cl atom. This intramolecular charge transfer causes the stability of the aluminum phthalocyanine chloride. The frontier molecular orbitals (Highest Occupied Molecular Orbital, HOMO, and Lowest Unoccupied Molecular Orbital, LUMO) are considered the most important orbitals in the molecule. These orbitals determine the way the molecule interacts with other species. The frontier orbital gap helps to characterize the kinetic stability and chemical reactivity of the molecule [22]. The calculated HOMOLUMO values are collected in Table 3. A three dimensional (3D) plot as shown in Fig. 6, shows the calculated HOMO/LUMO molecular orbitals at B3LYP/6-311G basis set, energy gap is 2.14 eV which indicates that our investigated compound is a promising structure for photovoltaic devices such as solar cells. The lowering of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap appears to be the cause of its enhanced charge transfer interaction.

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4. Conclusion In our work, attempts for the proper frequency assignments have been made for aluminum phthalocyanine chloride compound from FT-IR spectra. We used DFT/B3LYP level of theory utilizing 6-311G basis set to determine and analyzed harmonic frequencies and equilibrium geometries. Our calculations have been actually performed on a single molecule in the gaseous state in contrary to our experimental values recorded in both powder and thin film states in the presence of intermolecular interactions, so any discrepancy may be noted due to this fact. Similarity between calculated and experimental Raman spectra was demonstrated by using linear fitting function. The natural bond orbital (NBO) calculations were performed to study the atomic charge distribution of investigated compound. The dipole moment of the investigated compound is 4.68 Debye which indicates high reactivity to interact with the surrounding media and promising for photovoltaic devices fabrication. The optical energy band gap demonstrates the reliability of the electrochemical evaluation of LUMO and HOMO energy levels.

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[15] M. Ibrahim, A.A. El-Barbary, M.M. El-Nahass, M.A. Kamel, M.A.M. El-Mansy, A.M. Asiri, Spectrochim. Acta Part A 87 (2012) 202. [16] E.D. Glendening, A.E. Reed, J.E. Carpenter, F. Weinhod, NBO Version 3.1, TCI, University of Wisconsion. [17] Sundaraganesan, N.S. Ilakiamani, P. Subramani, B.D. Joshua, Spectrochim. Acta Part A 67 (2007) 628. [18] Hakkı Turker Akcay, Rıza Bayrak, Ertan Sahin, Kaan Karaoglu, Umit Demirbas, Spectrochim. Acta Part A 114 (2013) 531. [19] J.B. Lambert, H.F. Shurvell, L. Vereit, R.G. Cooks, G.H. Stout, "Organic Structural Analysis", Academic Press, New York, 1976. [20] Yuexing Zhang, Xianxi Zhang, Zhongqiang Liu, Hui Xu, Jianzhuang Jiang, Vib. Spectrosc. 40 (2006) 289. [21] M.M. El-Nahass, M.A. Kamel, A.F. El-deeb, A.A. Atta, S.Y. Huthaily, Spectrochim. Acta Part A 79 (2011) 443. [22] I. Fleming, "Frontier Orbitals and Organic Chemical Reactions", John Wiley and Sons, New York, 1976.

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Table S1 Computational optimized structural parameters for aluminum phthalocyanine chloride at HF/6-31G, HF/6-311G, B3LYP/6-31G and B3LYP/6-31G basis sets. Parameter

HF 6-31G

6-311G

B3LYP 6-31G 6-311G

Bond Length ( ) R(1,2) R(1,3) R(1,55) R(2,4) R(2,49) R(3,9) R(3,10) R(4,9) R(4,11) R(5,6) R(5,7) R(5,27) R(6,8) R(6,31) R(7,12) R(7,13) R(8,10) R(8,12) R(9,57) R(11,22) R(12,57) R(13,17) R(14,15) R(14,16) R(14,39) R(15,17) R(15,33) R(16,18) R(16,19) R(17,18) R(18,57) R(19,23) R(20,21) R(20,22) R(20,47) R(21,23) R(21,41) R(22,24) R(23,24) R(24,57) R(25,26) R(25,27) R(25,29) R(27,28) R(29,30)

1.3904 1.4488 1.3889 1.4459 1.3896 1.3988 1.2880 1.3464 1.3311 1.3981 1.4259 1.4010 1.4261 1.4010 1.3687 1.3297 1.3278 1.3709 1.9835 1.2957 1.9747 1.2870 1.3900 1.4471 1.3889 1.4501 1.3882 1.3469 1.3296 1.3990 1.9832 1.2973 1.3865 1.4597 1.3824 1.4596 1.3824 1.3762 1.3741 1.9864 1.0729 1.3720 1.4152 1.0715 1.0729

1.3892 1.4485 1.3875 1.4453 1.3884 1.4026 1.2852 1.3442 1.3342 1.3984 1.4214 1.4023 1.4215 1.4023 1.3698 1.3330 1.3322 1.3708 1.9785 1.2955 1.9672 1.2848 1.3891 1.4459 1.3880 1.4491 1.3872 1.3443 1.3335 1.4027 1.9787 1.2962 1.3852 1.4596 1.3806 1.4596 1.3806 1.3767 1.3758 1.9825 1.0707 1.3697 1.4170 1.0692 1.0707

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1.4110 1.4522 1.3976 1.4522 1.3976 1.3952 1.3273 1.3951 1.3273 1.4110 1.4522 1.3976 1.4522 1.3976 1.3952 1.3273 1.3273 1.3952 1.9955 1.3274 1.9954 1.3273 1.4110 1.4522 1.3976 1.4522 1.3976 1.3951 1.3273 1.3952 1.9955 1.3273 1.4110 1.4522 1.3976 1.4522 1.3976 1.3951 1.3952 1.9955 1.0851 1.3974 1.4124 1.0837 1.0851

1.4091 1.4506 1.3959 1.4506 1.3959 1.3952 1.3271 1.3952 1.3271 1.4091 1.4506 1.3959 1.4506 1.3959 1.3952 1.3271 1.3271 1.3952 1.9916 1.3271 1.9916 1.3271 1.4091 1.4506 1.3959 1.4506 1.3959 1.3952 1.3271 1.3952 1.9916 1.3271 1.4091 1.4506 1.3959 1.4506 1.3959 1.3952 1.3952 1.9916 1.0816 1.3951 1.4102 1.0804 1.0816

R(29,31) R(31,32) R(33,34) R(33,35) R(35,36) R(35,37) R(37,38) R(37,39) R(39,40) R(41,42) R(41,43) R(43,44) R(43,45) R(45,46) R(45,47) R(47,48) R(49,50) R(49,51) R(51,52) R(51,53) R(53,54) R(53,55) R(55,56) R(57,58)

1.3721 1.0715 1.0711 1.3831 1.0728 1.4031 1.0724 1.3818 1.0713 1.0711 1.3879 1.0724 1.3974 1.0724 1.3880 1.0711 1.0713 1.3812 1.0724 1.4038 1.0728 1.3825 1.0711 2.2831

1.3697 1.0692 1.0688 1.3825 1.0705 1.4026 1.0701 1.3812 1.0689 1.0687 1.3881 1.0701 1.3960 1.0701 1.3881 1.0687 1.0689 1.3809 1.0701 1.4029 1.0705 1.3823 1.0688 2.2505

1.3974 1.0837 1.0837 1.3974 1.0851 1.4124 1.0851 1.3974 1.0837 1.0837 1.3974 1.0851 1.4125 1.0851 1.3974 1.0837 1.0837 1.3974 1.0851 1.4124 1.0851 1.3974 1.0837 2.2659

1.3951 1.0804 1.0804 1.3951 1.0816 1.4102 1.0816 1.3951 1.0804 1.0804 1.3951 1.0816 1.4102 1.0816 1.3951 1.0804 1.0804 1.3951 1.0816 1.4102 1.0816 1.3951 1.0804 2.2473

Bond Angle (°) A(2,1,3) 106.7177 A(2,1,55) 121.0569 A(3,1,55) 132.2239 A(1,2,4) 106.5816 A(1,2,49) 121.6402 A(4,2,49) 131.778 A(1,3,9) 108.4835 A(1,3,10) 124.8357 A(9,3,10) 126.6604 A(2,4,9) 110.3047 A(2,4,11) 122.5315 A(9,4,11) 127.1556 A(6,5,7) 106.5448 A(6,5,27) 121.0038 A(7,5,27) 132.4505 A(5,6,8) 106.5562 A(5,6,31) 120.973 A(8,6,31) 132.4697 A(5,7,12) 109.6975 A(5,7,13) 123.9483 A(12,7,13) 126.3396 A(6,8,10) 124.0535 A(6,8,12) 109.6187 A(10,8,12) 126.3127 A(3,9,4) 107.9065 A(3,9,57) 124.81 A(4,9,57) 126.439 A(3,10,8) 125.0627 A(4,11,22) 123.1652 A(7,12,8) 107.5802

106.7013 121.0397 132.2567 106.5473 121.6796 131.7729 108.5393 124.7998 126.641 110.5789 122.2588 127.1561 106.5059 120.9345 132.5583 106.5114 120.9199 132.5673 109.8957 123.8733 126.2186 123.9189 109.8596 126.2088 107.6238 124.8275 126.736 124.8981 122.7946 107.2232

106.7360 121.2150 132.0483 106.7353 121.2168 132.0471 109.6100 123.3771 127.0019 109.6118 123.3746 127.0027 106.7370 121.2154 132.0469 106.7368 121.2166 132.0460 109.6098 123.3783 127.0011 123.3763 109.6103 127.0027 107.3033 125.8540 125.8624 123.3715 123.3692 107.3026

106.7499 121.1672 132.0822 106.7501 121.1636 132.0856 109.6751 123.3862 126.9284 109.6743 123.3893 126.9261 106.7499 121.1672 132.0822 106.7502 121.1636 132.0855 109.6752 123.3862 126.9283 123.3894 109.6741 126.9262 107.1442 125.9813 125.9839 123.3757 123.3753 107.1441

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A(7,12,57) A(8,12,57) A(7,13,17) A(15,14,16) A(15,14,39) A(16,14,39) A(14,15,17) A(14,15,33) A(17,15,33) A(14,16,18) A(14,16,19) A(18,16,19) A(13,17,15) A(13,17,18) A(15,17,18) A(16,18,17) A(16,18,57) A(17,18,57) A(16,19,23) A(21,20,22) A(21,20,47) A(22,20,47) A(20,21,23) A(20,21,41) A(23,21,41) A(11,22,20) A(11,22,24) A(20,22,24) A(19,23,21) A(19,23,24) A(21,23,24) A(22,24,23) A(22,24,57) A(23,24,57) A(26,25,27) A(26,25,29) A(27,25,29) A(5,27,25) A(5,27,28) A(25,27,28) A(25,29,30) A(25,29,31) A(30,29,31) A(6,31,29) A(6,31,32) A(29,31,32) A(15,33,34) A(15,33,35) A(34,33,35) A(33,35,36) A(33,35,37) A(36,35,37) A(35,37,38) A(35,37,39) A(38,37,39) A(14,39,37)

125.8354 125.7964 124.9725 106.5937 121.6563 131.7499 106.7231 121.0851 132.1904 110.2819 122.5109 127.1992 124.8013 126.7079 108.471 107.9242 126.4205 124.7989 123.0983 106.7008 121.5664 131.7326 106.6975 121.5849 131.7175 123.2162 127.5241 109.2512 123.1185 127.5493 109.324 108.0231 125.4742 125.5083 119.8539 118.8633 121.2827 117.7148 120.619 121.666 118.8525 121.3109 119.8366 117.7146 120.6217 121.6636 120.9192 117.434 121.6465 119.5507 121.4504 118.9988 119.193 120.9629 119.8441 117.4111

126.0221 125.988 124.8545 106.5519 121.6867 131.7612 106.7023 121.0532 132.2423 110.5696 122.2467 127.1777 124.7799 126.6653 108.5351 107.6316 126.7284 124.8242 122.7647 106.6798 121.5974 131.7224 106.6785 121.6053 131.7158 122.9731 127.5831 109.4374 122.9329 127.5912 109.4696 107.7288 125.6389 125.6693 119.8648 118.8507 121.2844 117.7817 120.536 121.6821 118.8458 121.2976 119.8566 117.7816 120.5376 121.6806 120.8755 117.4565 121.6677 119.5284 121.4573 119.0142 119.2333 120.9155 119.8511 117.4304

12

125.8585 125.8557 123.3712 106.7356 121.2157 132.0481 106.7357 121.2162 132.0474 109.6114 123.3761 127.0016 123.3752 127.0032 109.6107 107.3032 125.8632 125.8537 123.3699 106.7360 121.2151 132.0482 106.7359 121.2163 132.0471 123.3749 127.0029 109.6113 123.3746 127.0030 109.6115 107.3018 125.8592 125.8605 119.6193 119.1952 121.1854 117.5989 120.7136 121.6872 119.1959 121.1845 119.6196 117.5987 120.7136 121.6874 120.7124 117.5987 121.6885 119.6209 121.1847 119.1944 119.1938 121.1855 119.6206 117.5986

125.9820 125.9831 123.3756 106.7498 121.1672 132.0822 106.7501 121.1636 132.0856 109.6754 123.3861 126.9283 123.3894 126.9263 109.6741 107.1442 125.9826 125.9826 123.3753 106.7499 121.1672 132.0822 106.7501 121.1636 132.0855 123.3858 126.9287 109.6753 123.3891 126.9264 109.6742 107.1440 125.9819 125.9835 119.6314 119.2114 121.1571 117.6755 120.6442 121.6800 119.2094 121.1603 119.6303 117.6757 120.6436 121.6804 120.6436 117.6757 121.6804 119.6302 121.1603 119.2094 119.2115 121.1571 119.6314 117.6755

A(14,39,40) A(37,39,40) A(21,41,42) A(21,41,43) A(42,41,43) A(41,43,44) A(41,43,45) A(44,43,45) A(43,45,46) A(43,45,47) A(46,45,47) A(20,47,45) A(20,47,48) A(45,47,48) A(2,49,50) A(2,49,51) A(50,49,51) A(49,51,52) A(49,51,53) A(52,51,53) A(51,53,54) A(51,53,55) A(54,53,55) A(1,55,53) A(1,55,56) A(53,55,56) A(9,57,12) A(9,57,24) A(9,57,58) A(12,57,18) A(12,57,58) A(18,57,24) A(18,57,58) A(24,57,58)

120.8838 121.7049 121.0521 117.253 121.6946 119.6287 121.163 119.2083 119.2021 121.1784 119.6194 117.2541 121.0543 121.6913 120.8668 117.4291 121.7039 119.857 120.9615 119.1814 118.9829 121.4609 119.5561 117.4511 120.9029 121.6458 88.233 87.0103 101.7267 88.2078 103.0408 86.9893 101.6386 100.6945

120.8398 121.7296 121.0255 117.2496 121.7246 119.6089 121.1454 119.2457 119.2432 121.1518 119.605 117.2502 121.0266 121.723 120.8313 117.4389 121.7296 119.8577 120.9144 119.2279 119.0064 121.4625 119.531 117.4644 120.8675 121.6677 88.3216 86.8982 101.7006 88.2971 102.9913 86.8767 101.6715 100.8536

13

120.7133 121.6878 120.7119 117.5990 121.6887 119.6211 121.1845 119.1944 119.1937 121.1854 119.6209 117.5991 120.7120 121.6886 120.7133 117.5985 121.6878 119.6206 121.1846 119.1948 119.1939 121.1856 119.6204 117.5988 120.7127 121.6881 87.4655 87.4587 102.1454 87.4638 102.1481 87.4574 102.1496 102.1540

120.6442 121.6800 120.6436 117.6756 121.6804 119.6303 121.1603 119.2094 119.2114 121.1571 119.6314 117.6755 120.6442 121.6800 120.6436 117.6756 121.6804 119.6302 121.1603 119.2094 119.2115 121.1571 119.6314 117.6755 120.6442 121.6799 87.5226 87.5216 102.0007 87.5224 102.0013 87.5214 102.0011 102.0017

Table 1 Experimental and selected calculated vibrational wavenumbers (harmonic frequency (cm-1)), IR intensities and assignments for aluminum phthalocyanine chloride at B3LYP/6-311G basis set. Experimental Mode 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Bulk 3045 1496 1465 1332 1290 1166 1120 1066 952 904 819 763 728 644 617 568 512 428 414

Calculated at B3LYP/6-311G Wave number IR intensity Thin film Unscaled Scaled Rel. Abs. 3172 3050 9.23 s 2.47 1585 1652 1588 12.89 w 3.45 1496 1550 1490 1550 m 414.60 1457 1518 1459 33.37 m 8.92 1334 1377 1324 234.0 vs 62.58 1290 1344 1292 83.69 s 22.38 1166 1212 1165 7.40 vw 1.98 1118 1155 1111 131.2 vs 35.10 1066 1104 1061 105.9 s 28.33 1004 965 3.90 vw 1.04 898 917 882 7.01 s 1.87 848 815 4.23 w 1.13 757 776 746 374 vs 100.00 730 760 731 0.38 vs 0.10 661 693 666 0.00 0.00 615 669 643 5.49 vw 1.47 559 606 583 0.43 w 0.11 516 531 510 12.66 m 3.39 468 480 461 33.79 s 9.04 431 454 436 77.9 vw 20.84 432 415 0.02 vw 0.01 : stretching; β: in-plane-bending; : out-of-plane bending

14

Vibrational Assignment C-H C=C benzene C=N C=N, β C-H C=C benzene β C-H β C-H β C-H, ring breath Isoindole deformation ɣC-H ɣC-H Isoindole deformation ɣC-H ɣC-H Isoindole deformation Isoindole deformation Isoindole deformation Isoindole deformation Al-Cl Al-Cl Isoindole deformation

Table 2 Optimized calculations of total energy (a.u), zero point vibrational energy (kcal mol-1), rotational constants (GHz), Entropy (cal mol-1 K-1), dipole moment (D) and HOMO–LUMO energy gap (eV) for aluminum phthalocyanine chloride at HF/6-31G, HF/6-311G, B3LYP/631G and B3LYP/6-31G basis sets. Parameter Total Energy Zero Point Energy Rotational Constants Thermochemistry Total Translational Vibrational Rotational Dipole Moment HOMO-LUMO energy gap

HF/6-31G

HF /6-311G

B3LYP/6-31G

B3LYP/6-311G

-2357.675794 284.21338 0.08699 0.08681 0.04553

-2358.028143 281.41566 0.08721 0.08698 0.04560

-2369.504440 265.06878 0.08543 0.08543 0.04472

-2369.912856 262.96002 0.08561 0.08561 0.04480

176.071 44.927 93.066 38.078 6.6780 5.2099

176.086 44.927 93.086 38.072 6.5975 5.2251

183.837 44.927 100.780 38.130 4.8802 2.1526

183.838 44.927 100.787 38.124 4.6789 2.1422

15

Table 3 Theoretically computed frontier molecular orbital energies. States

Hartree

eV

HOMO-2

-0.26266

-7.14698

HOMO-1

-0.26266

-7.14698

HOMO

-0.20382

-5.54594

LUMO

-0.12509

-3.4037

LUMO+1

-0.12509

-3.4037

LUMO+2

-0.05795

-1.57682

16

Figures Caption Fig. 1. Optimized molecular structure of AlPcCl at B3LYP/6-311G basis set. (a) Side view. (b) Top view. Fig. 2. FT-IR spectrum for AlPcCl. (a) Bulk form, (b) Thin film form, (c) Calculated FT-IR at B3LYP/6-311g basis set. Fig. 3. Raman spectrum for AlPcCl. (a) Experimental in bulk form. (b) Calculated at B3LYP/6-311g basis set. Fig. 4. Correlation between experimental and calculated Raman vibrational data of AlPcCl (R: correlation coefficient; SD: standard deviation; N: number of data points). Fig. 5. Atomic charge distribution (au) for AlPcCl at B3LYP/6-311G basis set. Fig. 6. Calculated HOMO-LUMO energy gap for AlPcCl at B3LYP/6-311G basis set.

17

(a)

(b) Fig. 1. Optimized molecular structure of AlPcCl at B3LYP/6-311G basis set. (a) Side view. (b) Top view.

18

Fig. 2. FT-IR spectrum for AlPcCl. (a) Bulk form, (b) thin film form, (c) calculated FT-IR at B3LYP/6-311g basis set.

19

Fig. 3. Raman spectrum for AlPcCl. (a) Experimental in bulk form. (b) Calculated at B3LYP/6-311g basis set.

20

Fig. 4. Correlation between experimental and calculated Raman vibrational data of AlPcCl (R: correlation coefficient; SD: standard deviation; N: number of data points).

21

Fig. 5. Atomic charge distribution (au) for AlPcCl at B3LYP/6-311G basis set.

22

Eg = 2.14 eV

Fig. 6. Calculated HOMO-LUMO energy gap for AlPcCl at B3LYP/6-311G basis set.

23