Magnetic Circular Dichroism of Molecules in Dense Media: Relation Between Magnetic Circular Dichroism and Hammett's Constants

Abstract

The linear relation between the magnetic circular dichroism (benzene 'Aig -'B2-transition) of monosubstituted and 1,4-disubstituted benzenes and the substituent constants a and OfR are compared. In all cases, better linear correlations were found between the magnetic circular dichroism and aR. (benzene 'Aig --lB2, transition) data of monosubstituted and 1,4-disubstituted benzenes with both ar and aR. The experimental procedure and equipment are exactly the same as those described in the previous paper (2) and will not be described here. We have measured the MCD of X-C6H4-I (X=H, CH3, Cl, Br, I, OH, NH2, NO2, or CO2H), X-C6H4-NO2 (X=H, CH3, F, Cl, Br, I, NH2, NO2, or CO2H), and X-C6H4-CO2H (X=H, CH3, F, Cl, Br, I, OH, NH2, CN, or NO2) in methanol solutions. Data of the MCD of monosubstituted benzenes are taken from the previous paper (2).In Table 1

1H NMR Study on the Self-Association of Quinacridone Derivatives in Solution

“…It is expected that the strength of the stacking interaction would be increased by the substitution of halogens and decreased by the substitution of both CH 3 and C(CH 3 ) 3 , on the basis of the electron-donating nature of CH 3 and C(CH 3 ) 3 and the electron-withdrawing ability of F and Br in terms of Hammett’s substituent constants . Interestingly, the substitution of CH 3 and C(CH 3 ) 3 groups on the aromatic rings of QA-C 10 results in more negative Δ H (larger |Δ H |) of the self-association process, while the substitution of F and Br atoms on the aromatic rings gives rise to less negative Δ H (smaller |Δ H |) of the self-association process (Table ).…”