Temperature influence on the energy of nonspecific and specific interactions taking place between 4-aminophthalimide (4-AP) and homogeneous solvents

Abstract

Temperature induced spectral shifts of the 4-aminophthalimide (4-AP) emission spectra have been measured and compared to the predictions of the McRae solvent induced shift theory (J. Phys. Chem., 1957, 61, 562-572). Three moderately polar chloroalkanes selected as nonspecifically interacting media, and six hydrogen accepting or/and electron pair donating solvents have been used as the media in which the temperature influence on 4-AP-solvent interactions has been studied in the range of 180-320 K. Using the ab initio determined 4-AP ground state dipole moment and fitting appropriate expression originating from the mentioned theory to the shifts found in the chloroalkanes it has been possible to estimate the 4-AP excited state dipole moment, the probe excited state Onsager radius and its gas phase emission spectrum position. Using these values the thermochromic shifts of 4-AP emission spectra in hydrogen bond forming solvents have been predicted and compared to the experimental one. Temperature has been found to have different impact on the changes, upon excitation of the probe, in the mean values of the energies of different hydrogen bonds formed by 4-AP with solvents molecules.

Coumarin 153 emission thermochromism studied in non-specifically and specifically interacting solvents

“…Additionally, Dn HB temperature dependence found for C153, using the same method as in Ref. [1], is quite similar to the one found for 4-AP in the same 1-chloroalkanes. This observation indicates some universality in the observed temperature-induced changes in hydrogen bond energy.…”

“…Thus, the study reported previously for 4-AP [1] and in this paper for C153, although for model systems, can give important information, useful in the interpretation of observations made in much more complex systems, and can be of practical importance. Although this paper does not lead to definitive conclusions, it brings a new contribution to the hitherto knowledge of the influence of temperature on intermolecular interactions.…”

“…The group of selected solvents included the same solvents as in Ref. [1] and a few additional ones. Five 1-chloroalkanes, namely 1-chloropropane 99% (ClP, Aldrich), 1-chlorobutane 99.5% anhydrous (ClB, Aldrich), 1-chlorohexane 99% (ClH, Aldrich), 1-chlorooctane 99% (ClO, Aldrich) and 1-chlorodecane 98% (ClD, Aldrich), were used as the solvents interacting exclusively non-specifically with C153.…”

“…In a recent paper [1] we have attempted to explain the reasons for the thermochromic shifts of 4-aminophthalimide (4-AP) emission spectra, observed in several solvents. These spectra have been found to undergo significant bathochromic shifts with decreasing temperature in the range 180-320 K. An analysis of the shifts have shown that the position of the 4-AP emission spectra observed in three 1-chloroalkanes at different temperatures can be successfully predicted using the simple McRae [2] molecular interaction model with the dispersion term replaced by the one defined by London [3].…”

“…(1) and (2) predicts only the spectral shifts related to non-specific interactions taking place between the probe and the solvent. On the basis of its accordance with the experimental data obtained in 1-chloroalkanes, supposed to interact exclusively non-specifically with 4-AP, the model has been assumed of being able to predict similar ''non-specific'' shifts of the emission spectra position of 4-AP dissolved in specifically interacting solvents.…”