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Experimental and Computational Studies on L
-Histidinium DipicrateDihydrate
R Subaranjani, M Victor Antony Raj, J Madhavan
To cite this version:
Experimental and Computational Studies on
L - Histidinium DipicrateDihydrate
62R. Subaranjani1, a, M. Victor Antony Raj1, J. Madhavan1
1 – Department of Physics, Loyola College, Chennai, India a – [email protected]
DOI 10.2412/mmse.82.65.951 provided by Seo4U.link
Keywords: XRD, FT-IR, SHG, NLO, UV-visible, DFT.
ABSTRACT. Good quality single crystal of L-Histidiniumdipicrate dehydratewas grown by slow evaporation method. The structure of the grown crystal as determined by single crystal XRD diffraction analysis revealed that it belongs to the monoclinic system with space group P21. The presence of functional groups in the LHDP was confirmed by IR.
FT-IR spectrum of the grown crystal was recorded in the range 400 cm-1 to 4000 cm-1 using KBr pellet technique on
BRUKKER IFS FT-IR Spectrometer. Vibrational patterns and the good crytstallinity were indicated by powder X-ray diffraction method. The crystal system was identified by single crystal XRD method using ENRAF NONIUS CAD-4 single X-ray diffractometerwith MoKα radiation (λ=0.71073 Å). Thermogravimetric and differential thermal analyses revealed the thermal stability of the crystal. The Optical band gap energy (Eg) for the crystal was calculated to be 4.9eV.
Introduction.Nonlinear optical (NLO) materials are gaining enormous demand due to their wide applications in the recent technologies like, optical communications, optical switching, information storage and photonics technology [1, 2]. Organic crystals are of special interest compared to inorganic crystals.L-histidine gained the status of promising NLO materials after detailed research [3]. It is reported that L-histidinetetrafluoro borate has higher NLO properties than L-Arginine Phosphate (LAP). The function and role of histidine and its residues in living matter is characterized by the imidazole group. The NLO process requires materials that manipulate the amplitude, phase, polarization and frequency of optical beams. FTIR and UV–vis–NIR studies of the title compound are discussed.
Experimental Procedure.The synthesis of the title compound LHDP was achieved by adding L-histidine and picric acid (E-Merck) in 1:2 stoichiometric proportions in distilled water. The solution was thoroughly mixed to get a clear yellow solution which was filtered and kept aside. The solubility (g LHDP / 100ml H2O) of LHDP was measured by the method described by Wang et al (1999)[4]. The solubility curve is shown in Fig. 1. The crystals are grown by using the slow solvent evaporation technique at room temperature. Crystals of dimension up to 17 x 3 x 6 mm3 were obtained after a period of 45 days. The crystals are highly transparent and free from visible inclusions. Fig. 2 shows the photograph of as grown crystal of LHDP.
Characterization
Single crystal XRD Analysis. Single crystals of LHDP have been grown by slow evaporation technique and crystal system was identified by single crystal XRD method using ENRAF NONIUS CAD-4 single X-ray diffractometerwith MoKα radiation (λ=0.71073 Å). The crystal data is given in Table 1.
Fig. 1. Solubility curve of LHDP. Fig. 2. Photograph of as grown LHDP single crystal.
Powder X-ray Diffraction analysis.The powder XRD study was also carried out to check the correctness of the data and to identify the diffraction planes of the grown crystal. Experimental Powder XRD pattern is shown in Fig 3. Theoretically Simulated XRD pattern of LHDP single crystal is given in Fig 4. Both XRD patterns are almost similar in comparison.
Fig. 3. Experimentally obtained powder XRD. Fig. 4. Theoretically simulated powder XRD.
Computational Details. The equilibrium optimized geometrical parameters of LHDP molecule and the harmonic wavenumbers associated with its vibrational normal modes were calculated at B3LYP level of theory using the Gaussian 03 program package. The optimized geometry corresponding to the minimum on the potential energy surface has been obtained by solving self-consisting field equations iteratively. The optimized structural parameters were used to analyze all stationary points as minima for Infrared (IR) calculations at the same level of theory. By combining the theoretical results vibrational frequency assignments were made with a high degree of accuracy. The optimized geometrical parameters and fundamental vibrational frequencies were calculated using B3LYP/6-31(d, p).
Table 1. Crystal parameters of LHDP.
Empirical Formula C18H19N9O18 Unit cell dimensions
Formula weight 255.614 g/mol a = 6.6065(1) Ǻ b = 25.7004(2)Ǻ c =7.9629(2)Ǻ
α =γ=90° β=107.536°
Wave length 0.71073 Å
Molecular Geometry
The molecular structure along with numbering of atoms of LHDP was as shown in the Fig. 5.The selected vibrational assignment of LHDP molecule is given in Table 2.
Vibrational Analysis. The vibrational spectral assignments were carried out with the aid of normal co-ordinate analysis (NCA) followed by force field calculation with the same level of theory as was employed for the geometry optimization of the molecule. The title molecule LHDP has 64 atoms. It has 186 (3N – 6) normal vibrational modes .The theoretical and experimental wavenumbers are in fair agreement, and assignments of wavenumbers for different functional FT-IR spectrum of the grown crystal was recorded in the range 400 cm-1 to 4000 cm-1, using KBr pellet technique on BRUKKER IFS FT-IR Spectrometer. The experimental IR spectrum is compared with the results of B3LYP/6-31 G (d, p) calculation carried out for the title compound. The experimental FT-IR spectrum is shown in Fig. 6.
Fig. 5. Atomic numbering system of LHDP molecule.
Table 2. Selected Vibrational Assignments of LHDP molecule.
No Frequency cm -1 Spectroscopic Assignment B3LYP Experimental 1 2990.9085 2991 C-H st 2 2854.0305 2861 NH3asy st 3 1828.7112 1859 C O st 4 1637.6173 1617 NH3sy b 5 1587.4007 1588 NH3asydef 6 1333.3448 1326 CH opb 7 1449.8902 1438 OH ipb 8 1161.6827 1163 CH2 roc 9 1276.3151 1281 OH ipb 10 922.8158 914 NH3 roc 11 835.2978 833 CH opb 12 724.7566 712 R opb 13 626.8864 626 O-H opb 14 548.2281 555 C-C ben
St-stretching; syst- symmetry stretching;asyst- asymmetry stretching; ipb-in-planebending; opb- out-of-plane bending; roc – rocking; asydef – asymmetric deformation
NH3 Vibrations
deformation vibrations are observed as a very strong band at 1587 cm−1 in IR and the symmetric bending modes are observed as a strong band in IR at 1637 cm−1.Both the vibrations have its experimental values at1588 and1617 cm-1. The NH
3 rocking modes appear as a weak band in IR at 922 cm−1 and experimental shows at 914cm-1.
Hydroxyl vibrations
The OH stretching vibrations are sensitive to hydrogen bonding. The non-hydrogen-bonded or free hydroxyl group absorbs strongly in the 3600–3400 cm-1 region, whereas the existence of intermolecular hydrogen-bond formation can lower the O-Hstretching wavenumber around to the 3500 cm-1 region increase in IR intensity and breadth [6, 7].The strong band observed in IR at 3414cm-1 corresponds to OH stretching vibrations. The O–H out of plane bending vibration gives rise to a strong band in the region 700–600 cm−1[8]. The calculated values of OH group vibrations are in good agreement with the experimental results.
Fig. 6. Experimentally obtained FT-IR spectrum of LHDP.
UV-Vis study. The optical absorption spectrum of the grown LHDP crystal was recorded UV–Visible spectrophotometer in the wavelength range from 200 nm to 1000 nm. The recorded spectrum is shown in Fig. 7.In 280 nm, the lower cut-off wavelength of the crystal is found and thus ascertain fact that the crystal can be used for laser applications.Using Tauc relation a graph was plotted to estimate the band gap values. Fig. 8 shows the plot of (αhν)2 versus hν, where α is the optical absorption coefficient and hν is the energy of the incident photon. The energy gap (Eg) is determined by extrapolating the straight line portion of the curve to (αhν)2 = 0. From this graph, the band gap (Eg) is found to be 4.9eV.
Thermal analysis. The thermo gravimetric analysis and differential thermal analysis (TG/DTA) of LHDP crystal are displayed in Fig 9. The first stageofdecompositioncommencesat 179°C and ends at 310°C. The next weight loss occurs between 310°C to500°C with the loss percentage of 15.6.The third weight loss is between 500°Cand 900°C. The TG study of the LHDP crystal shows that the crystal is stable up 179°C. LHDP decomposes completely as no residue remains after 900°C. The DTA traces coincide well with the TGA traces.
Fig. 9. TG-DTA curves of LHDP single crystal.
Summary. Good quality single crystals of LHDP were grown by the slow evaporation solution growth technique. The lattice parameters were confirmed using single crystal X-ray diffraction analysis. The functional groups were ascertained by FT-IR and Raman studies. The energy gap (Eg) is determined by extrapolating the straight line portion of the curve to (αhν)2 = 0. From this graph, the band gap (Eg) is found to be 4.9eV.The thermal behavior of the grown LHDP was studied using TG–DTA.
References
[1] Kumaresan P., MoorthyBabu S., Anbarasan P.M., Opt. Mater. 30 (2008) 1361. http://dx.doi.org/10.1016/j.optmat.2007.07.002
[2] Prasad P.N., Williams D.J., Introduction to nonlinear optical effects in organic molecules and polymers, Wiley, New York, 1991.
[3] Marcy H.O., Rosker M.J., Warren L.F., Cunningham P.H., and Thomas C.A., Optics Letters, 20 (3) (1995) 252. DOI: 10.4236/jmmce.2009.85035
[4] Wang J, Ren M, Wang S, Qu Y, Spectrochim. Acta A, 78(3) (1999) 1126-1132 http://dx.doi.org/10.1016/j.saa.2010.12.064
[5] Silverstein R. M, Webster. F. X., Spectrometric Identification of Organic Compounds., John Wiley and sons, New York, 2003.
[8] Colthup N.B, L.H. Daly, S.E. Wiberley., Introduction to Infrared and Raman Spectroscopy., Academic Press, New York, 1990.
Cite the paper R. Subaranjani, M. Victor Antony Raj, J. Madhavan, (2017). Experimental and Computational Studies on L -
Histidinium DipicrateDihydrate . Mechanics, Materials Science & Engineering, Vol 9. doi
