Structural Evolution and Properties of Praseodymium Antimony Oxochlorides Based on a Chain-like Tertiary Building Unit.

Unveiling the structural evolution of single-crystalline compounds based on certain building units may help greatly in guiding the design of complex structures. Herein, a series of praseodymium antimony oxohalide crystals have been isolated under solvothermal conditions via adjusting the solvents used, that is, [HN(CH 2 CH 3 ) 3 ][Fe II (2,2'-bpy) 3 ][Pr 4 Sb 12 O 18 Cl 15 ]·EtOH ( 1 ) (2,2'-bpy = 2,2'-bipyridine), [HN(CH 2 CH 3 ) 3 ][Fe II (2,2'-bpy) 3 ] 2 [Pr 4 Sb 12 O 18 Cl 14 ) 2 Cl]·N(CH 2 CH 3 ) 3 ·2H 2 O ( 2 ), and (H 3 O)[Pr 4 Sb 12 O 18 Cl 12.5 (TEOA) 0.5 ]·2.5EtOH ( 3 ) (TEOA = mono-deprotonated triethanolamine anion). Single-crystal X-ray diffraction analysis revealed that all the three structures feature an anionic zig-zag chain of [Pr 4 Sb 12 O 18 Cl 15- x ] n as the tertiary building unit (TBU), which is formed by interconnections of praseodymium antimony oxochloride clusters (denoted as {Pr 4 Sb 12 }) as secondary building units. Interestingly, different arrangements or linkages of chain-like TBUs result in one-dimensional, two-dimensional layered, and three-dimensional structures of 1 , 2 , and 3 , respectively, thus demonstrating clearly the structural evolution of metal oxohalide crystals. The title compounds have been characterized by elemental analysis, powder X-ray diffraction, thermogravimetric analysis, and UV-Vis spectroscopy, and the photodegradation for methyl blue in an aqueous solution of compound 1 has been preliminarily studied. This work offers a way to deeply understand the assembly process of intricate lanthanide-antimony(III) oxohalide structures at the atomic level.