Solvation is a ubiquitous phenomenon associated with molecules in solutions. It often determines the equilibria of molecular systems and the rates of chemical reactions. Van der Waals interactions (a general term) includes weak interactions among noncharged compounds and it contributes significantly to solvation. The distinct observation of van der Waals interaction between solvent and porphyrin derivatives is reported herein. Bis(imidazolylporphyrinatozinc) structures connected through a 1,3-butadiyne moiety give two types of coordination polymers, E (extended) and S (stacked) polymers, exclusively. E polymers have larger solvent-accessible surface areas than the corresponding S polymers. Therefore, E polymers are better solvated than S polymers, providing an indicator of solvation and desolvation for the solvents used. A simple method (like a litmus test) was developed to evaluate the solvation ability of various solvents. Sixty-seven solvents and liquid compounds were tested, under the same conditions, using a conventional UV/Vis spectrometer. The results revealed a new liquid group with high solvation ability towards the porphyrins, and clarified van der Waals interaction assisted by secondary interaction on the substituents. The indicator system should contribute to the solution chemistry of molecules and materials, and to supramolecular chemistry interactions among hetero components.
Bis(imidazolylporphyrinatozinc) molecules linked through a1 ,3-butadiynylene moiety respond to the solvents they are dissolved in to afford exclusively extended (E) or stacked (S) supramolecular polymers. This system is expected to be as olvation/desolvation indicator. However, the principles underlying the solvent-dependent formation of the two types of polymers and the mechanism of the transformation between them are unclear.T he formation of the polymers is considered to depend on the two types of complementaryc oordination bonds that can be formed and the p-p interactions between the porphyrins. In this study,t he contributionsa nd solventd ependence of both the coordination bonds and the p-p interactions have been investigated. The results clearly indicate that the coordination bonds are weaklyo rl ittle solvent-dependent, and that the p-p interactions functione ffectively only in the inner porphyrins of the S-polymer and are strongly solvent-dependent. Thermodynamic analysis revealed that the formation of the E-or Spolymer in solution is determined by the total energiesa nd the typeo fs olventu sed. Thet ransformation of the E-to Spolymer wasi nvestigated by gel permeation chromatography.T he kinetics of the transformationw ere also determined.T he role of the terminal imidazolylporphyrinatozinc moietiesw as also investigated:T he results indicatet hat the transformation from the E-to S-polymer occurs by an exchange mechanism between the polymers, induced by attack of terminal free imidazolyl groups on ap olymer to zinc porphyrins on other polymers.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.
A new solvent scale, solvation ability (SA), was developed to arrange solvents in the order of their SA for large π-conjugated compounds. The SA of a solvent was determined in a binary solvent system of an assessed solvent and a standard "good" solvent (GS) or "poor" solvent (PS), chloroform or methylcyclohexane, respectively, in the presence of two types of solvation/desolvation indicators, 1Zn 2 and 2Zn 2 . The latter comprises bis(imidazolylporphyrinatozinc) linked via a 1,3-butadiynylene moiety having linear alkyl and hydrophilic side chains, respectively. GSs and PSs give extended (E-) and stacked (S-) supramolecular polymers of the indicators, respectively. SA values are defined as vol % of the standard solvent added to an assessed solvent to give the balance point where comparable amounts of E-and S-polymers of the indicators coexist. GSs and PSs have positive and negative signs, respectively. In this study, the SA of 25 solvents was determined. The SA values with indicator 1Zn 2 were as follows: ethyl acetate (−81), hexane (−66), toluene (−50), cyclohexane (−47), CCl 4 (−25), chloroform (50), and nitrobenzene (79).
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