Crystal structures, optical analysis and theoretical calculations of two thiosemicarbazide and semicarbazide derivatives based on triphenylamine-thiophene

Two new thiosemicarbazide and semicarbazide derivative based on triphenylamine-thiophene, (E)-2-((5-(4-(diphenylamino)phenyl)thiophen-2-yl)methylene)hydrazine-1-carboxamide (L1) and (E)-2-((5-(4-(diphenylamino)phenyl)thiophen-2-yl)methylene)hydrazine-1-carbothioamide (L2), were synthesized and fully characterized by IR, 1H NMR, 13C NMR, MS and single crystal X-ray structural determination. Their structures are similar, contained the same donor groups of triphenylaminyl units (TPA), the core thienyl ring (thienyl-C), and the =N-NH-CX-NH2 group (X = O, S) with different hetero atom. The absorption/emission maxima (in aspects of both wavelength and intensity) is altered by variation of the =N-NH-CX-NH2 groups. To clarify the influence mechanism of the hetero atom in photophysical properties, the computational results of them under state specific PCM/TD1 PBE1PBE method were performed in DCM solvent and illustrated by hole-electron transition method, which the excitation and de-excitation of them are illustrated by hole-electron transition method. Furthermore, ADCH charge indicated that the electron is transferred from the donor groups of TPA and thienyl-C to acceptor group (=N-NH-CX-NH2). The results illustrate that L2 transfers more electron from the donor groups to acceptor group (=N-NH-CS-NH2) than that (=N-NH-CO-NH2) of L1.