Absorption and luminescence as a function of pH for carboxylic acid-functionalized ReI tricarbonyls

被引:12
作者
Costa, I
Montalti, M
Pallavicini, P
Perotti, A
Prodi, L
Zaccheroni, N
机构
[1] Univ Pavia, Dipartimento Chim Gen, I-27100 Pavia, Italy
[2] Univ Bologna, Dipartimento Chim G Ciamician, I-40126 Bologna, Italy
关键词
rhenium carbonyls; luminescence; stability constants; pH-indicator;
D O I
10.1016/S0022-328X(99)00541-0
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
Six new ester- and carboxylic acid-derivatives of the fac-Re-I(CO)(3)(2,2'-bipyridine)Cl and [fac-Re-I(CO)(3)(2,2'-bipyridine)(pyridine)]CF3SO3 type have been prepared, in which the functions reside on the bipy or py fragments, in their 5- and 3-positions, respectively: the compounds are Re-I(CO)(3)(bi(pyCOOCH(3))Cl (2), Re-I(CO)(3)(bipyCOOH)Cl (3), [Re-I(CO)(3)(bipyCOOH)(pyCOOCH(3))]CF3SO3 [Re-I(CO)(3)(bipyCOOCH(3))(pyCOOH)]CF3SO3 (5), [Re-I(CO)(3)(bipyCOOCH(3))(pyCOOCH(3))]CF3SO3 (6) and [Re-I(CO)(3)(bipyCOOH)(pyCOOH)]CF3SO3 (7). These Re-I complexes are air- and moisture-stable, and it has been possible to study their properties in aqueous solution (water-dioxane 1:4), as a function of pH. The pK(a)s of the carboxylic acid(s)-containing species have been determined by means of potentiometric titration experiments and the absorbing and emitting properties of the six complexes related to the deprotonation processes. In particular, it has been possible to ascertain that the MLCT band of the rhenium chromophore is related, as expected, to an electron transfer process taking place always towards the bipy fragments, even in the py containing species 4-7, independently on the substituent tester, carboxylic acid or carboxilate) residing on it. Interestingly, the sharp and intense luminescence versus pH variation found for 3 makes it a suitable candidate for a luminescence-based pH sensor. (C) 2000 Elsevier Science S.A. All rights reserved.
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页码:267 / 273
页数:7
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