1. International Conference on Multifunctional Materials for future applications
Synthesis, atomic packing and optical studies of a novel organic compound: 3-(4-Chloro-3-nitrophenylimino) methyl) phenol
R. N. Rai and Priyanka Pandey
Department of Chemistry, Centre of Advanced Study, Banaras Hindu University,
Varanasi , India
*Corresponding author, address: Ph: , Fax:
Fluorescence
Introduction
Spectral Analysis
FTIR .
The design and synthesis of organic non-centrosymmetric chromophores as nonlinear optical (NLO) materials has attracted the attention of scientist in recent years. NLO materials have great potential, especially in optical communication, information processing, frequency doubling and integrated optics [1, 2].
Organic NLO materials have many advantages over inorganic materials such as large nonlinear optical coefficients, great opportunity for manipulations in synthesis and low cost [3].
An intramolecular charge transfer associated with 𝜋-electron linkage from the donor atom to an acceptor atom can produce large second and third order non-linearities. Such compounds have different application in optical data storage, nonlinear optical materials, light emitting diodes, etc. [4, 5]. Such materials are of demand for the designing of different molecular electronic devices.
With a view of the above importance, we have synthesized 3-(4-Chloro-3-nitrophenylimino) methyl) phenol (CNAHB) and studied various properties such as spectral, optical and nonlinear optical properties of the newly synthesized organic molecular compound.
In the FT-IR spectrum of the solid CNA, an intense and well-defined peak is observed at 3212 cm−1 due to the primary amino group. The peak at 1248 cm−1 is due to the CO vibrations. From the FT-IR study of the CNAHB, a new strong absorption band at cm−1 appeared due to CH=N of CNAHB and simultaneously disappearance of primary amine peak and the structural change due to the interaction between CNA and HB confirms the formation of complex.
Fig.6 View of hydrogen bonding in CNAHB crystal
NMR Study
UV-Vis Absorption Study
The 1H and 13C NMR spectra of CNA, HB and CNAHB have been recorded in DMSO solvent. In the 13C NMR of the complex, the peak for CHO carbon of HB (193 ppm) was absent. The peak for amino group of CNA (4.009 ppm) is disappeared in 1H NMR. However, a new peak is observed at 8.401ppm in 1H NMR, which is due to the hydrogen of (CH=N) and appearance of new peak in 13C NMR at ppm is due to (–CH=N) carbon. These observations are suggesting the formation of a new addition compound.
The optical absorption spectra of CNA, HB and CNAHB have been recorded in the range of 200–700 nm at room temperature in methanol solution (1.0 X 10 ‒ 5 M) and have been shown in Fig.7. The UV-Vis absorption spectrum of CNA show two peaks at 244 and 377 nm which is ascribed to the n→𝜎* and n→π* transitions, respectively, due to the presence of the amino group (NH2). The two bands have appeared in absorption spectrum of HB. One at 252 nm attributed to the π→π* transition, and other strong band at 315 nm is attributed to the n→π* transition. In the complex, band at 280 nm is due to π→π* transition of electrons of aromatic ring and a band at 330 nm is attributed to π→π* transition of imine group. The absorption spectrum of complex shows the hypsochromic (blue) shift with hyperchromic (higher absorbance) shift for absorption maxima to that of CNA which might be due to increase in extent of conjugation.
Synthesis and Experimentation
Powder XRD
The novel organic compound CNAHB was synthesized via solid state reaction by taking 1:1 molar ratio as conceived idea from phase diagram study of 4-Chloro-3-nitroaniline (CNA) and 3-Hydroxy benzaldehyde (HB).
The single crystal of complex was grown by slow evaporation technique from saturated solution of methanol at 300 K.
The grown crystal was studied for various characterizations such as NMR, FTIR, single crystal XRD, powder XRD and UV-Vis. To assess the non-linear optical performance of CNA, HB and CNAHB the materials were illuminated with μm radiation of a Nd:YAG laser.
It is evident from the powder XRD pattern of complex Fig.3 that some new peaks has appeared which could not be assigned for either of parent components and again confirm the formation of a new compound.
Results and Discussion
Phase Diagram Study
Phase diagram study shows the formation of an addition/complex compound (CNAHB) with congruent melting point with two eutectics lying on both sides of complex. The mole fraction composition of CNA for E1, E2 and the complex are 0.10, and 0.50, respectively, and their corresponding melting points are 99.0, 96.0 and oC, respectively as shown in Fig.1.
Fig. 3: Powder XRD plots of CNA, HB and CNAHB
Fig.7 UV-Vis spectra of CNA, HB and CNAHB
Single Crystal XRD
Nonlinear optical study
The single crystal of the complex was grown from saturated solution of methanol using slow evaporation technique at 300 K. From the single crystal X-ray diffraction analysis of the complex inferred that the complex has crystallized in orthorhombic unit cell with P space group (CCDC No ). The lattice parameters as well as various other crystallographic parameters of the complex are given in Table.1 While the ORTEP view and numbering scheme of the complex is shown in Fig.4, the molecular packing is given in Fig.5 and the hydrogen bonding pattern is shown in Fig.6.
The nonlinear optical spectra of the complex material and the parent components were recorded. Higher intensity signal was recorded for HB whereas no signal was observed for CNA but the green emission was observed with the CNAHB complex and the intensity of which was in between CNA and HB.
NMR Study
NMR Study
Conclusion
The phase diagram study between HB and CNA organic compounds show the formation of a novel organic compound in 1:1 ratio, which melts congruently at 158 oC, and two eutectics lying on either side of the complex. The spectroscopic studies suggest the formation of new adduct (CNAHB). Single crystal X-ray diffraction analysis of complex inferred that it crystallizes in orthorhombic unit cell with P space group. UV-Vis study of complex shows blue shift (40 nm) in max of absorption than CNA due to increase in extent of conjugation in the CNAHB.
Fig.4 ORTEP view and numbering scheme of CNAHB
Fig.1 Phase diagram of CNA−HB system
Differential Scanning Calorimetry Study
Acknowledgements
The experimentally determined enthalpy (∆Hfus) of fusion of complex was found to be kJ mol−1. The thermal stabilities of both the parent components and the complex compound at different temperature have shown in Fig.2.
Authors would like to thank UGC, New Delhi, India for financial support and Head, Department of Chemistry, B.H.U for providing infrastructure.
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Fig.5 Molecular packing of CNAHB in unit cell
Fig.2 DSC curves of CNA, HB and CNAHB