Stereochemically Active and Inactive Lone Pairs in Two Room-Temperature Phosphorescence Coordination Polymers of Pb2+ with Different Tricarboxylic Acids
journal contributionposted on 09.05.2019, 00:00 by Xu-Sheng Gao, Hai-Jie Dai, Mei-Juan Ding, Wen-Bo Pei, Xiao-Ming Ren
Two new Pb2+-based coordination polymers (CPs), [Pb2(HBTC)2(DMF)] (1) and [Pb(HPTC)] (2), have been synthesized under solvothermal condition; herein, H3BTC and H3PTC represent 1,3,5-benzenetricarboxylic acid and 2,4,6-pyridine tricarboxylic acid, respectively. Both 1 and 2 were characterized by microanalysis, infrared spectra (IR), thermal gravimetric analyses (TGA), and powder X-ray diffraction (PXRD) techniques. Single-crystal structural analysis indicates that 1 and 2 show different coordination sphere around Pb2+ ions and distinct coordination frameworks. The I1O2 type three-dimensional (3D) nonporous metal–organic framework forms in 1, where the Pb2+ ion shows holo-directed coordination geometry, while the I0O2 type two-dimensional (2D) coordination polymeric layered structure forms in 2, where Pb2+ ion shows a hemidirected coordination sphere and the 6s2 lone electron pair in Pb2+ ion is stereochemically active. The two CPs emit intense and long-lasting greenish phosphorescence in air at room temperature, with absolute quantum yields of 1.2% for 1 and 4.7% for 2 and decay lifetimes of 0.73 ms for 1 and 1.52 ms for 2.
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powder X-ray diffractionH 3 BTCstructure formscoordination polymersroom temperature0 O 2 typeDMFHBTC2 showdecay lifetimeselectron pairH 3 PTCquantum yieldssolvothermal conditionPXRDhemidirected coordination sphereInactive Lone PairsCPholo-directed coordination geometry1.52 msDifferent Tricarboxylic Acids1 O 2 typeRoom-Temperature Phosphorescence Coordination Polymersgravimetric analysesTGAcoordination sphereIR0.73 msPb 2coordination frameworks