Designing of some photo-luminescent materials based on a new mesogenic asymmetrical azine series

Abstract

[1-(4-(n-alkoxy))-2-(4′-dodecyloxy)benzylidene]hydrazine, (where, n-alkoxy: O(CH2)nH, n = 1,2,3,4,5,6,7,8,9,10,16 or 18) compounds (Asymmetrical azine series-II) were prepared as a part of our continuous works in the designing of hydrophobic azine compounds as photo-luminescent liquid crystalline materials, and compared with 1,2-bis[4-(n-alkoxy)benzylidene]hydrazines, (where, n-alkoxy: O(CH2)nH, n = 1,2,3,4,5,6,7,8,9,10,12,16 or 18) (Symmetrical azines), and [1-(4-propyloxy)-2-(4'-(n-alkoxy))benzylidene]hydrazine, (where, n-alkoxy: O(CH2)nH, n = 1,2,4,5,6,7,8,9,10,12,16 or 18) (Asymmetrical azines series-I), that have been prepared in our previous works. The synthesis has been preformed following an efficient and practical method (simple mixing of hydrazine hydrate with 4-dodecyloxybenzaldehyde and appropriately 4-(n-alkoxy)benzaldehydes in acidic medium and under ambient conditions). Moreover, a series of silver(I) complexes based on [1-(4-(n-alkoxy))-2-(4′-dodecyloxy)benzylidene]hydrazine (where, n-alkoxy: O(CH2)nH, n = 1,2,3,4,5,6,7 or 8) compounds were synthesized (linear-binuclear type complexes with the general formula [Ag2(L)(NO3)2] were obtained). The prepared organic and organic–inorganic hybrid compounds were characterized using different techniques: microelemental analysis and spectral data (I.R, U.V–Vis, 1HNMR, 13C{1H}NMR, 2D 1H-1H-COSY, 2D 1H-13C- HSQC and mass spectra) as well as molar conductivity measurements for silver(I) complexes. Liquid crystalline behavior of the prepared compounds were studied using polarized light optical microscopy (POM) and confirmed with differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD) techniques. Furthermore, the luminescent properties of all the prepared compounds were also investigated. The studies revealed that all the organic and organic–inorganic hybrid compounds are photo-luminescent, while only organic azine compounds are liquid crystalline materials.