Comparison studies of hybrid lead halide [MPb 2 X 7 ] 2- (M = Cu, Ag; X = Br, I) chains: band structures and visible light driven photocatalytic properties.

By using transition-metal (TM) complex cationic dyes as structure-directing agents and photosensitizers, a series of inorganic-organic hybrid metal halides, namely, [TM(2,2'-bipy) ₃ ]AgPb ₂ I ₇ [TM = Ni (1), Co (2) and Zn (3)], [Co(2,2'-bipy) ₃ ]CuPb ₂ Br ₇ (4) and [TM(2,2'-bipy) ₃ ]AgPb ₂ Br ₇ [TM = Ni (5) and Fe (6)], have been solvothermally prepared and structurally characterized. Compounds 1-3 feature 1D [AgPb ₂ I ₇ ] ^2- chains built from the condensation of [Ag ₂ I ₆ ] dimers and [Pb ₄ I ₁₄ ] tetramers, and compounds 4, 5 and 6 contain similar 1D [CuPb ₂ Br ₇ ] ^2- and [AgPb ₂ Br ₇ ] ^2- chains, respectively. UV-Vis diffuse reflectance measurements reveal narrow band gaps of 1.75-2.18 eV for compounds 1-6, which lead to efficient and stable photocatalytic degradation activities over organic pollutants under visible light irradiation. Among the title compounds, sample 5 shows the highest photocatalytic degradation activity. The possible mechanism for their stable photocatalytic activities is proposed based on the experimental and theoretical studies.