The tetra-azamacrocyclic nickel(II) complex [Ni11(4)]2+, has been synthesized, structurally characterized and investigated as a fluorescence switch. [Ni11(4)]2+, which in solution displays an emission spectrum typical of naphthalene derivatives, undergoes a deprotonation at moderately basic pH values (pK(a) = 8.8 in 4:1 MeCN-water solution) involving the dienic moiety of the macrocyclic system. As the deprotonated species, [Ni11(8)]+, is distinctly less emissive than its dienic analogue, the fluorescence of [Ni11(4)]2+ in a 4:1 MeCN-water solution is quenched by addition of a base and revived by addition of an acid. So, a reversible variation of the emission intensity can be obtained by simply varying the pH of the solution. (C) 2000 Elsevier Science S.A.
Searching for new fluorescence switches: Naphthalene-containing metal complexes whose emission can be controlled by pH variations
Michele Zema
2000-01-01
Abstract
The tetra-azamacrocyclic nickel(II) complex [Ni11(4)]2+, has been synthesized, structurally characterized and investigated as a fluorescence switch. [Ni11(4)]2+, which in solution displays an emission spectrum typical of naphthalene derivatives, undergoes a deprotonation at moderately basic pH values (pK(a) = 8.8 in 4:1 MeCN-water solution) involving the dienic moiety of the macrocyclic system. As the deprotonated species, [Ni11(8)]+, is distinctly less emissive than its dienic analogue, the fluorescence of [Ni11(4)]2+ in a 4:1 MeCN-water solution is quenched by addition of a base and revived by addition of an acid. So, a reversible variation of the emission intensity can be obtained by simply varying the pH of the solution. (C) 2000 Elsevier Science S.A.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
