Covalent Synthesis of Two Hybrids Composed of Dawson-Type Polyoxometalate and Porphyrin with Remarkable Third-Order Optical Nonlinearities Reflecting the Effect of Polyoxometalates
Covalent Synthesis of Two Hybrids Composed of Dawson-Type Polyoxometalate and Porphyrin with Remarkable Third-Order Optical Nonlinearities Reflecting the Effect of Polyoxometalates
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由道森型多金属氧酸盐和卟啉组成的两种杂化物的共价合成，具有反映多金属氧酸盐效应的显着三阶光学非线性
DOI：
10.1021/acs.inorgchem.6b03155
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发表时间：
2017
影响因子：
4.6
通讯作者：
Li Yanqin
中科院分区：
文献类型：
--
作者：
Asif Hafiz Muhammad;Zhou Yunshan;Zhang Lijuan;Shaheen Nusrat;Yang Di;Li Jiaqi;Long Yi;Iqbal Arshad;Li Yanqin
合成了两种新的卟啉-多金属氧酸盐杂化化合物[(C4H9)4N]10H2[{COHNC(CH2O)3P2V3W15O59}2C44N4H28]·CH3CN1，和[(C4H9)4N)]5H[COHNC(CH2O)3P2V3W15O59{C44H29N4}]·CH3CN2，，并用元素分析、粉末X射线衍射、FT-IR、1H(31P，51V)、MALDI-TOF-MS、UV-Vis光谱和循环伏安等手段对其进行了表征。实验结果表明，虽然所有化合物都表现出显著的三阶光学非线性，但杂化1和杂化2优于相应的卟啉前体(杂化1的前驱54-N-N′(1，3-tetrahydroxy-2-(dihydroxymethyl)propan-4-diyl)benz-diamide，10，15，20-triphenyl卟啉的分子第二超极化率γ=8.0×10-28esu，杂化2的前驱54-N-N′(1，3-tetrahydroxy-2-(dihydroxymethyl)propan-4-diyl)benz-diamide，10，15，20-triphenyl卟啉的分子第二超极化率γ=2.6×10-28esu)。杂化1(γ=12.9×10-2 8esu)优于杂化2(γ=12.2×10-2 8esu)，反映了更多的聚甲醛部分共价键合在卟啉基团上，对三阶光学非线性的影响更显著。同时，多酚与卟啉的结合导致了显著的荧光猝灭(杂化1的荧光强度比相应的卟啉前体降低了97%，杂化2的荧光强度降低了80%)，表明从卟啉部分到多金属氧酸盐部分有很强的电子转移。较低的跃迁能、较小的单态和三态激发态能量差以及较快的系间交叉(ISC)过程有利于增强杂化1和杂化2的非线性光学响应，这可能是杂化1和杂化2优于杂化1和杂化2的原因，也是杂化1和杂化2优于相应的卟啉前体的原因。
Two new porphyrin-polyoxometalate hybrids, namely, [(C4H9)4N]10H2[{COHNC(CH2O)3P2V3W15O59}2C44N4H28]·CH3CN1, bearing two covalent-bonded Wells–Dawson-type polyoxometalates (POMs), and [(C4H9)4N)]5H[COHNC(CH2O)3P2V3W15O59{C44H29N4}]·CH3CN2, bearing one covalent-bonded POM, have been synthesized and thoroughly characterized by means of elemental analysis, powder XRD, FT-IR,1H (31P,51V) NMR, MALDI-TOF-MS, UV–vis spectra, and cyclic voltammetry measurement. Experimental results demonstrate that while all the compounds show remarkable third-order optical nonlinearities, the hybrids1and2are superior to their corresponding porphyrin precursors (molecular second hyperpolarizability γ = 8.0 × 10–28esu for 54-N-N′(1,3-tetrahydroxy-2-(dihydroxymethyl)propan-4-diyl)benz-diamide,10,15,20-triphenyl porphyrin that is the precursor for the hybrid1, γ = 2.6 × 10–28esu for 54-N-(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)benz-amide,10,15,20-triphenyl porphyrin that is the precursor for the hybrid2), and the hybrid1(γ = 12.9 × 10–28esu) is superior to the hybrid2(γ = 12.2 × 10–28esu) reflecting more POM moieties covalently bonded to the porphyrin moiety exerting more significant influence on the third-order optical nonlinearities. Meanwhile, attachment of POMs on the porphyrin results in significant fluorescence quenching (fluorescence intensity is decreased 97% for the hybrid1and 80% for the hybrid2with respect to that of their corresponding porphyrin precursors) indicating strong electron transfer from porphyrin moiety to the polyoxometalate moiety. Lower transition energy, small energy difference between singlet and triplet excited states, and faster intersystem crossing (ISC) process of the hybrids are favorable to enhance the NLO responses of hybrids1and2resulting from the facile electron transfer from the porphyrin moiety to the Dawson POM moiety when the hybrids are subjected to laser irradiation, which is thought to be responsible to the superior of the hybrid1to hybrid2and the superior of the hybrids to their corresponding porphyrin precursors as well.