CU(TMEN)(ACAC)(-VISIBLE SPECTROSCOPIC PROBE FOR THE SURFACE HYDROGEN-BOND ACCEPTING ABILITY OF ANIONS ADSORBED TO SILICA AND CHEMICALLY FUNCTIONALIZED SILICAS() AS AN ULTRAVIOLET)

A linear solvation energy relationship is employed to characterize the specific surface polarity of organically modified silica particles. T he surface polarity of silicas can be quantitatively described by thre e independent terms, the dipolarity/polarizability (pi), the hydrogen -bond donating ability (alpha), and the hydrogen-bond accepting (HBA) ability (beta). These terms can he defined using the Kamlet-Taft solve nt parameters alpha, beta, and pi as a reference system. The HBA prop erty beta of organically modified silica surfaces and anions adsorbed to silica has been determined by measuring the energy of the d-d tran sition (nu(max)) of adsorbed Cu(tmen)(acac)X-+(-) [X- = Cl-, Br-, NO3- , CH3CO2-, and B(C6H5)(4)(-)]. nu(max) correlates linearly with the be ta parameter of the solvents. Cu(tmen)(acac)B+(C6H5)(4)(-) is used as a beta indicator for the organically functionalized silicas because th e nonnucleophilic anion B(C6H5)(4)(-) does not interact with residual silanols. Cu(tmen)(acac)Cl-+(-), Br-, NO3-, and CH3CO2- are adsorbed t o residual silanols due to the higher basicity of the counteranion. Th e correspondence between the residual silanol acidity and the basicity of the functional groups of specific silica samples is discussed.