Hood Bethany R, de Coene Yovan, Jones Claire F, Deveaux Noah, Barber Jack M, Marshall Charlotte G, Jordan Chloe A, Halcovitch Nathan R, Champagne Benoît, Clays Koen, Fielden John
Department of Chemistry, Lancaster University, Lancaster LA1 4YW, U.K.
School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K.
Inorg Chem. 2025 Apr 28;64(16):8408-8420. doi: 10.1021/acs.inorgchem.5c00915. Epub 2025 Apr 14.
Three linear, dipolar arylimido-polyoxometalate (POM) and one 2-dimensional -functionalized arylimido-polyoxometalate charge transfer chromophore, with diphenylacetylene bridges, have been synthesized and studied by spectroelectrochemistry, hyper-Rayleigh scattering (HRS), and DFT/TD-DFT calculations. The linear systems show that with julolidinyl (Jd) and -NTol donor groups, the alkyne bridge yields high second-order nonlinear optical (NLO) coefficients β (Jd, β = 318 × 10 esu; -NTol, β = 222 × 10 esu), indeed the Jd compound gives the highest NLO activity of any organoimido-POM to date with minimal decrease in transparency. The -functionalized 2D () POM derivative showed increased activity over its monofunctionalized analogue with no decrease in transparency, although the NLO response was only minimally two dimensional. Spectroelectrochemistry and TD-DFT calculations showed switchable linear optical responses for the monofunctionalized derivatives due to the weakened charge transfer character of the electronic transitions in the reduced state, while TD-DFT also indicated potential for switched NLO responses. These have been demonstrated by electrochemistry-HRS for the Jd compound, but cyclability is limited by relatively poor stability in the reduced state. IR and CV studies for these sterically protected arylimido polyoxometalates indicate that decomposition proceeds via a breakdown of the {Mo} cluster in the reduced state, rather than simple solvolysis of the Mo≡N bond.
三种线性偶极芳基亚胺基多金属氧酸盐（POM）和一种二维功能化芳基亚胺基多金属氧酸盐电荷转移发色团（带有二苯乙炔桥）已被合成，并通过光谱电化学、超瑞利散射（HRS）以及密度泛函理论/含时密度泛函理论（DFT/TD-DFT）计算进行了研究。线性体系表明，对于带有久洛尼定基（Jd）和 -NTol供体基团的情况，炔烃桥产生了较高的二阶非线性光学（NLO）系数β（Jd，β = 318×10 esu；-NTol，β = 222×10 esu），实际上，Jd化合物是迄今为止所有有机亚胺基 -POM中具有最高NLO活性且透明度降低最小的。功能化的二维（）POM衍生物比其单功能化类似物表现出更高的活性且透明度没有降低，尽管NLO响应仅略微具有二维性。光谱电化学和TD-DFT计算表明，由于还原态电子跃迁的电荷转移特性减弱，单功能化衍生物具有可切换的线性光学响应，而TD-DFT还表明存在切换NLO响应的潜力。这已通过Jd化合物的电化学 -HRS得到证明，但循环性受到还原态相对较差稳定性的限制。对这些空间位阻保护的芳基亚胺基多金属氧酸盐的红外和循环伏安研究表明，分解是通过还原态下{Mo}簇的分解进行的，而不是Mo≡N键的简单溶剂解。
