Synthesis and spectroscopy of anionic tridentate benzimidazole-pyridine carboxylate and tetrazolate chromophore ligands
摘要:
We report on seven new anionic benzimidazole-pyridine carboxylate and tetrazolate tridentate (NNO)-N-boolean AND-O-boolean AND and (NNN)-N-boolean AND-N-boolean AND ligands that are modified with chromophore (phenyl, biphenyl, naphthyl) and solubilizing groups. The ligands are UV chromophores with the lowest-energy absorption maxima at 312-335 nm and with the molar absorption coefficients of (20-25) x 10(3) M-1 cm(-1) in DMSO solution. The ligands form neutral complexes with trivalent lanthanides and sensitize the red luminescence of europium. The triplet state energies of the deprotonated ligands, which were measured from the phosphorescence spectra of their lanthanum complexes at 77 K, are in the range of (18.8-21.1) x 10(3) cm(-1). We also describe synthesis of non-symmetric pyridines that are 2,6- and 2,4,6-substituted with hydroxymethyl, carboxaldehyde, and carbonitrile groups. (C) 2014 Elsevier B.V. All rights reserved.
制备了一系列三齿苯并咪唑取代的吡啶-2-羧酸,在苯并咪唑环的6位带有卤素,甲基或烷氧基,其中还含有可溶的N烷基链。配体形成中性的九坐标镧,euro和ter络合物,这是通过对八个结构的X射线晶体学分析确定的。镧系元素离子周围的配位多面体接近于三重三角棱镜,其配体以上-下-下的方式排列。配位体充当络合物中的集光生色团,其最大吸收范围为321–341 nm(ε =(4.9–6.0)×10 4 M -1 cm -1)以及21,300至18,800 cm -1之间的三重态能量; 最大的红移发生在溴和电子给体的烷氧基取代基上。配体有效地敏化铕的发光与整体的量子产率()和观察到的寿命(τ OBS)分别达到71%和3.00毫秒,在固体状态下和52%和2.81毫秒,在CH 2氯2在室温下。铕(的辐射寿命5 d 0)电平量τ弧度= 3.6-4.6毫秒和敏化效率η SENS = (τ弧度/τ OBS)对于大