Abstract
Abstract Two new lead(II) coordination polymers with isomeric thiophenecarboxylates, namely [Pb(2tpCOO)2]n (1) and [Pb(3tpCOO)2(H2O)]n (2) (2tpCOO− = thiophene-2-carboxylate, 3tpCOO− = thiophene-3-carboxylate), were synthesized and characterized. Single crystal X-ray crystallography revealed a distorted pentagonal pyramidal geometry {PbO6} around Pb in 1 and a distorted dodecahedral geometry {PbO8} in 2. The distortion derived from the presence of 6 s2 inert electron pair on lead(II), which was confirmed by DFT calculations. The topological classification of obtained polymers has been performed, disclosing the SP 1-periodic net (4,4)(0,2) and gek1 topology in 1 and 2, respectively. Interactions stabilising crystal structures were also confirmed by Hirshfeld surface analysis. Fluorescence properties allowed to distinguish the type of thiophene-monocarboxylic acid isomers. The luminescence intensity which derived from π → π∗ and/or n → π∗ transitions is higher in 2tpCOOH. Photoluminescent properties of complexes 1 and 2 are much more enhanced in comparison to starting ligands. The emission bands in the complexes can be attributed to the ligand-to-metal charge transfer (LMCT) as a change in the intraligand transitions. Additional low energy emissions with large Stokes shifts appeared and were assigned to the metal-centered (MC) transitions involving s and p lead(II) orbitals, which were also confirmed by DFT calculations. Moreover, both complexes were characterized by infrared spectroscopy and thermal stability analysis.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
