Department of Chemistry, University of Delhi, Delhi 110 007, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2013 Sep;113:386-92. doi: 10.1016/j.saa.2013.05.006. Epub 2013 May 14.
The synthesis of a new N-substituted fluorescent probe based on a bis-benzimidazole diamide N(2),N(2')-bis[(1-(4-methylbenzyl)-benzimidazol-2-yl)methyl]biphenyl-2,2'-dicarboxamide (L1) with a biphenyl spacer group and its trinuclear copper(II) complex [Cu3(L1)3Cl3]·3Cl·3H2O] has been described. X-ray studies shows that the trinuclear complex crystallizes as [{Cu3(L1)3Cl3}2·6Cl·13CH3CN·2H2O] in triclinic space group P-1 with two independent molecules in the asymmetric unit. Each copper(II) adopts a distorted penta-coordinated geometry in each unit. The fluorescence spectra of L1 in methanol show an emission band centered at 300 nm. This band arises due to benzimidazolyl moiety in the ligating system. The diamide L1 in the presence of Fe(3+) show the simultaneous 'quenching' of (300nm) and 'enhancement' of (375 nm) emission band. The new emission band at 375 nm is attributed to intra ligand π-π(*) transition of the biphenyl moiety. While Cu(2+) and Ag(+) show only the quenching of the 300 nm band. No such behavior was observed with other metal ions like Ni(2+), Co(2+), Mn(2+), Mg(2+), Zn(2+) and Pb(2+). The quenching constant with Fe(3+), Ag(+) and Cu(2+) are calculated by the Stern-Volmer plots.
描述了一种新型 N-取代荧光探针的合成，该探针基于联苯间隔基的双苯并咪唑二酰胺 N(2)，N(2')-双[(1-(4-甲基苄基)-苯并咪唑-2-基)甲基]联苯-2,2'-二羧酸酰胺 (L1) 和三核铜(II) 配合物 [Cu3(L1)3Cl3]·3Cl·3H2O]。X 射线研究表明，三核配合物在三斜晶系 P-1 空间群中结晶为 [{Cu3(L1)3Cl3}2·6Cl·13CH3CN·2H2O]，每个不对称单位中有两个独立的分子。每个铜(II) 在每个单元中采用扭曲的五配位几何形状。在甲醇中，L1 的荧光光谱显示出一个发射带，中心位于 300nm。该带归因于配位系统中的苯并咪唑基部分。在存在 Fe(3+)的情况下，二酰胺 L1 同时显示出 (300nm) 的“猝灭”和 (375nm) 发射带的“增强”。新的 375nm 发射带归因于联苯部分的内配体 π-π(*)跃迁。而 Cu(2+)和 Ag(+)仅显示 300nm 带的猝灭。其他金属离子如 Ni(2+)、Co(2+)、Mn(2+)、Mg(2+)、Zn(2+)和 Pb(2+)则没有观察到这种行为。通过 Stern-Volmer 图计算了与 Fe(3+)、Ag(+)和 Cu(2+)的猝灭常数。
