Abstract:The synthesis, characterization, and spectroscopic properties of novel nonperipherally tetrasubstituted metallophthalocyanines (zinc, cobalt, copper, manganese, and indium) bearing 4 (7-(trifluoromethyl)quinolin-4-yl)oxy units has been reported. The new compounds have been characterized using UV-Vis, IR, 1 H NMR,and mass spectroscopic data. The absorption properties of these new complexes were compared to those of peripherally substituted phthalocyanine derivatives. Based on the structural, spectroscopic, and absorption studies, it was found that the substitution effect altered the electronic structures significantly. The results provide useful information to understand the effect of peripheral or nonperipheral substitution on the properties of this macrocyclic ring. Photophysical properties with zinc(II) phthalocyanine were found, including electronic absorption and fluorescence quantum yield. The fluorescence of the complex was investigated in DMF and it was found that benzoquinone was an effective quencher.
Steady-state and time-resolved fluorescence techniques were used to study the thermodynamics of binding of a neutral polarity-sensitive guest, the methyl 2-naphthalenecarboxylate (2MN), with three cucurbiturils (CBn; n ¼ 6, 7 and 8) in water. Association constants (K) were obtained from nonlinear regression analysis of the fluorescence intensity against [CB] in the 5 -458C range. 2MN complexed with CB7 exhibited a 1:1 stoichiometry (K < 10 3 M 21 at 258C); however, it hardly did with CB6 (K , 10 M 21 ) and it did not with the larger CB8 macrocyclic ring. The (1:1) 2MN:CB7 complexation process was accompanied by a small unfavourable enthalpy change and was, therefore, entropically governed. Molecular mechanics and molecular dynamics calculations in the presence of water were also used to study the geometry of the complexes formed and the driving forces responsible for their formation. The results were compared with those previously obtained for the complexation of the same guest, 2MN, with natural a-, b-and g-cyclodextrins.
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