- A 1,8-naphthalenediol-based unsymmetrical dinucleating ligand
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A facile synthesis of 2-formyl-1,8-naphthalenediol is reported. Its potential as a general precursor for the preparation of unsymmetrical multidentate chelating ligand systems based on 1,8-naphthalenediol is demonstrated by the synthesis of the dinucleating ligand L4- (H 4L = N,N′-bis(2-(1,8-naphthalenediol)methylidene) propylenediamine). Reaction of H4L with copper acetate results in the formation of the unsymmetrical dinuclear CuII complex [LCu 2] (3), which has been structurally characterized by single-crystal X-ray diffraction. One CuII ion is coordinated by a N 2O2 compartment of L4- and the other Cu II ion is coordinated by an O4 compartment of L 4- while they are bridged by two aryloxide functions of L 4-. A dimerization of two molecules of 3 to a tetranuclear entity 32 occurs through formation of weak apical Cu-O interactions. Analysis of the temperature dependent magnetic susceptibility measurements (2-290 K) established a strong intradimer exchange coupling J12 = -371 cm-1. This strong superexchange interaction fits nicely in a magneto-structural correlation which has been established for dinuclear bis(phenoxide)-bridged CuII complexes demonstrating the electronic equivalence of the aryloxides of a phenol and 1,8-naphthalenediol. The Royal Society of Chemistry 2005.
- Glaser, Thorsten,Liratzis, Ioannis,Froehlich, Roland
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- Optically Triggered Stepwise Double-Proton Transfer in an Intramolecular Proton Relay: A Case Study of 1,8-Dihydroxy-2-naphthaldehyde
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1,8-Dihydroxy-2-naphthaldehyde (DHNA), having doubly intramolecular hydrogen bonds, was strategically designed and synthesized in an aim to probe a long-standing fundamental issue regarding synchronous versus asynchronous double-proton transfer in the excited state. In cyclohexane, DHNA shows the lowest lying S0 →S1 (π-π) absorption at ~400 nm. Upon excitation, two large Stokes shifted emission bands maximized at 520 and 650 nm are resolved, which are ascribed to the tautomer emission resulting from the first and second proton-transfer products, denoted by TA and TB, respectively. The first proton transfer (DHNA → TA) is ultrafast (-1 and (3.6 ps)-1, respectively. The fast equilibrium leads to identical population lifetimes of ~54 ps for both TA and TB tautomers. Similar excited-state double-proton transfer takes place for DHNA in a single crystal, resulting in TA (560 nm) and TB (650 nm) dual-tautomer emission. A comprehensive 2D plot of reaction potential energy surface further proves that the sequential two-step proton motion is along the minimum energetic pathway firmly supporting the experimental results. Using DHNA as a paradigm, we thus demonstrate unambiguously a stepwise, proton-relay type of intramolecular double-proton transfer reaction in the excited state, which should gain fundamental understanding of the multiple proton transfer reactions.
- Peng, Chia-Yu,Shen, Jiun-Yi,Chen, Yi-Ting,Wu, Pei-Jhen,Hung, Wen-Yi,Hu, Wei-Ping,Chou, Pi-Tai
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p. 14349 - 14357
(2015/11/27)
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- Highly selective visual detection of Cu(II) utilizing intramolecular hydrogen bond-stabilized merocyanine in aqueous buffer solution
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A Cu2+-specific colorimetric sensor 1, which is stabilized by an intramolecular hydrogen bonding, was designed and developed. The color of 1 changes from purple to blue on addition of 1.0 μM Cu2+ in aqueous buffer solution, which can be detected by the naked eye. The analytical detection limit for Cu2+ by the naked eye is as low as 1.0 μM. The stoichiometry for 1 and Cu2+ in complex is 2:1 in aqueous solution.
- Guo, Zhao-Qi,Chen, Wei-Qiang,Duan, Xuan-Ming
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supporting information; experimental part
p. 2202 - 2205
(2010/08/06)
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