Ditopic N-Crowned 4-(p-Aminophenyl)-2,6-diphenylpyridines: Implications of Macrocycle Topology on the Spectroscopic Properties, Cation Complexation, and Differential Anion Responses

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• 作者：Beatriz Garc&iacute ; a-Acosta ; Ram&oacute ; n Mart&iacute ; nez-M&aacute ; ñ ; ez ; F&eacute ; lix Sancen&oacute ; n ; Juan Soto ; Knut Rurack ; Monika Spieles ; Eduardo Garc&iacute ; a-Breijo ; Luis Gil
• 刊名：Inorganic Chemistry
• 出版年：2007
• 出版时间：April 16, 2007
• 年：2007
• 卷：46
• 期：8
• 页码：3123 - 3135
• 全文大小：275K
• 年卷期：v.46,no.8(April 16, 2007)
• ISSN：1520-510X

文摘

A family of N-crowned 4-p-(aminophenyl)-2,6-diphenylpyridines DA (1-6) has been synthezised, characterized,and studied as potential hosts for the signaling of cationic and anionic guests. The ditopic probes contain twocoordination sites, a monodentate 2,6-diphenylpyridine and an anilino group with macrocycles of different ring size,denticity, and type of secondary heteroatom (O and/or S). X-ray structure analysis of aza-oxa-thia-crowned 5indicated a largely planar chromophore. Optical spectroscopic and electrochemical studies revealed that the anilino-type donor (D) and the 2,6-diphenylpyridine acceptor (A) are strongly ages/gifchars/pi.gif" BORDER=0 >-conjugated, entailing intense intramolecularcharge-transfer absorption bands at 340 nm. Binding studies with protons and metal ions (M = Cu²⁺, Zn²⁺, Hg²⁺,Fe³⁺, Pb²⁺, Ni²⁺, Cd²⁺) showed shifts of the band to the visible (440 nm) when coordination at the pyridine groupoccurs, strengthening its acceptor character. In contrast, no band in the visible is formed if binding takes place atthe anilino group. Three different responses were found for various pairs of DA and M: selective metal coordinationto D or A as well as coordination at both sites. A selective response was found for 5 and Hg²⁺. Because of themultitude of coordination-induced effects, the DA-M ensembles were further employed for differential anion sensing.In this protocol, the addition of an anion X to a certain, weakly coordinated DA-M can (i) lead to the formation ofa ternary ion pair complex (DA-M-X), (ii) change the preference for A or D coordination, (iii) induce dissociationof the complex, or (iv) can have no effect. Various patterns of absorption changes were obtained as a result ofdifferent responses (i)-(iv) of the DA-M's in the presence of various X's. Data analysis yielded recognition patternsfor acetate, F^- and CN^-, demonstrating the potential of simple chromogenic host-guest pairs for differential anionsignaling.