New Cd2+, Pb2+ complexes with acylhydrazidate molecules from in situ acylation reactions

Abstract

Through employing the hydrothermal in situ acylation of N₂H₄ with aromatic dicarboxylic acids, four new acylhydrazidate-coordinated complexes, [Cd₂(pth)₄(phen)₂(H₂O)₂]·H₂O (pth = phthalhydrazidate; phen = 1,10-phenanthroline) 1, [Cd₃(dcpth)₆(phen)₂(H₂O)₂] (dcpth = 4,5-dichlorophthalhydrazidate) 2, [Cd(pdh)₂(H₂O)₂] (pdh = pyridine-2,3-dicarboxylhydrazidate) 3 and [Pb(sdpth)(phen)] (sdpth = 4,4′-sulfoyldiphthalhydrazidate) 4, were obtained. X-ray analysis revealed that (i) isomerization and deprotonation of acylhydrazide molecules also occurred; (ii) compound 2 possesses a one-dimensional (1-D) double-chain structure, in which dcpth exhibits three types of coordination modes; (iii) compound 4 shows a 1-D castellated single-chain structure; (iv) the adjacent uncoordinated acylamino groups form a hydrogen-bonded dimer, via which compounds 2–4 self-assemble into different two-dimensional (2-D) supramolecular networks. In the solid state, only compound 3 emits green light (λ_em = 525 nm), while in an aqueous solution, compounds 1, 3 and 4 all emit light. Density functional theory (DFT) calculations indicate that the emission at 470 nm for compound 1 corresponds to a charge transfer within the phen molecule, whereas the emission at 400 nm for compound 3 corresponds to a charge transfer within the pdh molecule.