Raman spectra for benzophenone in CCl4 highlighting the regions subject to solvatochromism (red), specifically the ν(C=O) stretching mode (a) and the aromatic proton stretching region ν(Car—Har) (b).
Observed dependence of the benzophenone solvatochromic Raman shift ν(C=O) on the Onsager reaction field |E Ons| of the encapsulating solvent. Solvent shifts are grouped into four general categories including alcohol hydrogen bonding (yellow), alcohol bare shifts (green), halogen bonding/aromatic (blue/grey), and general polar/nonpolar solvents (red). The dashed regression line given by is provided for the general solvent category (R 2 = 0.93).
Calculated Raman shift ν(C=O) relative to hexane versus as a function of the Onsager reaction field |E Ons| arising from the solvent environment (B3LYP/cc-pVTZ). Shifts are grouped into categories corresponding to implicit solvent only for general polar/nonpolar solvents (red), implicit solvent for alcohols (green), explicit solvent with hydrogen bonding for alcohols (yellow), implicit halogenated solvent (dark blue), explicit halogenated solvent with halogen bonding (teal), and explicit halogenated solvent with hydrogen bonding (light blue). The dashed regression line given by represents a fit to all calculated implicit solvent points (R 2 = 1.00).
Representative geometries for explicit solvent DFT calculations with halogenated solvents. Configurations include direct halogen (a) and hydrogen (b) contacts with the benzophenone carbonyl.
Dependence of the benzophenone ν(C=O) lineshape within primary and secondary alcohol solvents. Systems are plotted from top to bottom in order of decreasing Onsager reaction field .
Representative geometries for explicit solvent DFT calculations with alcohols. Configurations correspond to methanol (a), ethanol (b), 1-propanol (c), and 2-propanol (d).
Cross correlation between calculated νDFT(C=O) and observed νObs(C=O) values for the benzophenone C=O stretch relative to hexane. Physically plausible series are represented by squares and comprise the general polar/nonpolar solvents (red), implicit solvent for alcohols (green), explicit solvent with hydrogen bonding for alcohols (yellow), explicit halogenated solvent with halogen bonding (teal), and explicit halogenated solvent with hydrogen bonding (light blue). Series which are not believed to be physically representative, specifically the implicit halogenated solvents and implicit toluene, are represented by grey crosses. The dashed line represents a regression νObs(C = O) = 0.423νDFT(C = O) − 2.7419 for physically plausible series (R 2 = 0.87).
Titration of benzophenone in acetonitrile with water on an equivalent by equivalent basis as monitored by the ν(C=O) band solvatochromic shift and lineshape. Pure benzophenone is plotted at top with increasing concentrations water in consecutive, descending plots.
Representative geometries for the interaction of water with benzophenone in acetonitrile solutions. Configurations correspond to single (a) and double (b) molecule water chains in a hydrogen bonding network originating at the benzophenone carbonyl.
Decomposition of the ν(C=O) stretch in benzophenone into two Kubo–Anderson functions during titration of water into a benzophenone/acetonitrile solution. The two fitting functions are depicted alongside their sum. Experimental and fit band centers are presented outside and inside of parentheses, respectively.
General properties of the ν(C=O) spectral feature for water: benzophenone/CH3CN solutions at several physically significant ratios.
Kubo–Anderson fit parameters for titration of water into the benzophenone/CH3CN system. Units are specified for ω0 in cm−1, ⟨ω2(1)⟩ in cm−2, and τ c in ps. The index corresponding to the particular Kubo–Anderson fitting function is denoted in parentheses.
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