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Abstract— Samples of quinine sulfate or bisulfate from a number of vendors have been examined. The light absorptivity and fluorescence excitation spectra of quinine bisulfate prepared from six sources of hydrated quinine sulfate had satisfactory agreement with each other. The solid samples of quinine sulfate or bisulfate showed good agreement (2.2 per cent relative difference) in their fluorescence quantum yields but the one commercial solution of quinine sulfate was 20 per cent low. The relative fluorescence quantum yield of quinine sulfate was evaluated with excitation from 240 through 400 nm and was found to have no unexplainable deviations from a constant value. It is suggested that some of the conflicting results in the literature may be due to the common practice of using a different spectral bandwidth for absorbance measurements than that used for excitation.

Studies were made of solutions of 1-octanol and 1-butanol in n-decane using the infrared absorption of the first overtone of the O-H stretch vibrations of the monomer and selfassociation polymers. Evaluation was made on 1-octanol solutions from 5 to 100°, without making use of a priori self-association models. Evaluations were performed by three methods involving comparisons of: (I) the monomer absorbance and the total alcohol concention, (II) the monomer absorbance and the polymer absorbance, and (III) a combination of I and II. The following new assignments were made: (1) the end O-H of linear selfassociation polymers do not contribute significant absorbance at the monomer peak in the first overtone region; (2) the monomer molar absorptivity is constant with temperature;(3) the usual "dimer" peak at 1.528 µ cannot be due to a O-H • O-H dimer as its absorbance varies directly proportionally to that of the monomer (it is tentatively assigned to an alcohol-solvent interaction); (4) the remainder of the polymer absorption is assigned solely to tetramers; and (5) the tetramers give partially overlapping peaks which are due to O-H bonds in two different tetramers. Thermodynamic values indicate a linear and a cyclic tetramer. The linear with three bonds has a AH of -16.5 kcal/mole and the cyclic with four bonds has a AH of -20.3 kcal/mole. Thus within the limits of error, all O-H first overtone absorption is explained by assigning a monomer in equilibrium with two tetramers. This holds from 10-4 M to neat 1-octanol over a 95°t emperature range. Data from other workers for other alcohols in CCk are evaluated and found to be consistent with the present assignments. Much more self-association of alcohols was observed in n-decane than was observed in CCh. In particular, kinetic data involving alcohols are explained by the physical model described.N. Y" 1959.

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Contrary to previous reports, the wavelength position of a fluorescence emission band need not remain fixed with variation of the wavelength of excitation. Certain fluorescent compounds with rotatable auxochromic groups are shown to exhibit a fluorescence band shift (B shift) in numerous solvents. It is postulated that the B shift is due to the fluorescent molecule existing in at least two different "average" conformations, each with its own distinct electronic energy transitions. These conformations can be considered as being stabilized by the interaction of the solvent with the molecule in both its ground and electronically excited states. The B shift then results from the excitation of different proportions of these two conformations. 2-Aminopurine, , '-biphenol, 6-ethoxyquinaldine, luminol, 6-methoxyquinaldine, 6-methoxyquinoline, and quinine are shown to have B shifts.

Spectrophotometric evidence is presented for the existence of a 1:1 complex between carbon tetrachloride and the monomer of 1-octanol absorbing at the wavelength of the monomer (1.41 µ ). The nonbonded solvent "free" monomer concentration was calculated from the concentration of the cyclic self-association tetramer using equilibrium constants previously determined with re-decane as the solvent. The concentration of the CCh "bonded" portion of the monomer was determined by difference from the total monomer concentration. The 1:1 complex is explained on the basis of an O-H • • • Cl hydrogen bond with CCI4 serving as the proton acceptor. The equilibrium constant between CCI4 and 1-octanol was determined at 5, 30, and 45°over the complete range of possible concentrations. The formation of the 1:1 complex was found to have a small enthalpy change (~-0.5 kcal mol-1) and an average equilibrium constant of 0.096 ± 0.001. Although 0.096 is rather small, it effectively changes the total monomer-total self-association tetramer equilibrium quotient from a value of 774 M~3 in re-decane down to 50 M~3 in CCh at 25°. Thus the true equilibrium constant for 1-octanol is 15 times larger than the quotient normally measured in CCI4. Since only half of the monomer is solvent "free" in dilute CCh solutions, previous hydrogen bond equilibrium studies involving O-H groups in CCI4 are in serious error. This is particularly true where the degree of self-association was used to determine the self-association species. Calculations were also performed determining the concentrations of all major species in solution using just the added concentration of 1-octanol in CC14 and the derived equilibrium constants. For example, an average relative deviation of only 3.1% was found between the calculated and the measured concentration of the monomer at concentrations up to neat alcohol for 40 determinations at three different temperatures.