Green synthesis, characterization and optical properties of eutectics and 1:1 intermolecular compounds: N,N-dimethylaminobenzaldehyde–anthranilic acid and 2-(4-(dimethylamino)benzylideneamino)benzoic acid–p-nitroaniline systems

Abstract

Phase diagrams of N, N-dimethylaminobenzaldehyde (DMAB)–anthranilic acid (AA) and 2-(4-(dimethylamino)benzylideneamino)benzoic acid (DMABAB)–p-nitroaniline (PNA) systems, determined by the thaw-melt method, give two eutectics and a 1:1 intermolecular compound (IMC) in each case. Appropriate amounts (10 g) of each of the eutectics and the IMCs were prepared by a green synthetic method involving a solid state reaction without any solvent. These materials were characterized by X-ray diffraction, thermal and spectral methods and the optical properties of the pure components and the IMCs were studied. While negative values of heat of mixing in the case of a DMAB–AA system suggest clustering of molecules in both eutectic melts, those of positive value in $\hbox {E}_{1}$ and negative value in $\hbox {E}_{2}$ of the DMABAB–PNA system indicate the formation of a quasi-eutectic structure in $\hbox {E}_{1}$ melt and clustering of molecules in $\hbox {E}_{2}$ melt. The IMC of DMAB–AA system shows strong dual emission with two $\lambda _{\mathrm{max}}$ one at 380 nm and the second at 450 nm with a total quantum efficiency of 0.49. The IMC of DMABAB–PNA system also shows a similar observation with two $\lambda _{\mathrm{max}}$ one at 390 nm and second at 435 nm with a total quantum efficiency of 0.31.