A Solvation/Desolvation Indicator Based on van der Waals Interactions between Solvents and Porphyrins

Abstract

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.

Solvoluminescence of Cerium(III) Thiocyanate Complex

“…[22,23] The association constants of SCN À to Ce III ion, which are estimated from both the UV/Visa bsorption and emission spectra, decreaseb yo ne order of magnitude when each coordination of SCN À proceeds up to three equivalents. [25,26] Figure 4s hows plots of the emission peak position against donor number,i nw hich at least three differentg roups can be distinguished: non-coordinating(blue circle), oxygen-coordina-ting (purple circle)a nd nitrogen-coordinating solvents (green circle). Figure 2s hows the distribution of Ce III species based on the association constants.…”

“…[24] The excitation spectra were correlatedw ith the emissions pectra ( Figure S7 in the Supporting Information).T od etermine the nature of the solvoluminescence, the emission peaks in the solvents were plotted against severals olventp arameters, such as empirical solvent scales (donor number, p*a nd E T(30) ), dielectric constant (e), and the dipolar-dipolar interaction function( ( eÀ1)/(e + 1)À(n 2 À1)/ (n 2 + 1);F igures4 and FiguresS8a nd S9 in the Supporting Information). [25,26] Figure 4s hows plots of the emission peak position against donor number,i nw hich at least three differentg roups can be distinguished: non-coordinating(blue circle), oxygen-coordina-ting (purple circle)a nd nitrogen-coordinating solvents (green circle). Solvents having neither oxygen nor nitrogen atoms, such as toluene and dichloromethane, are difficult to coordinate to Ce III iona nd could be classified as non-coordinating solvents.…”

Mechanistic Study of the Solvent‐Dependent Formation of Extended and Stacked Supramolecular Polymers Composed of Bis(imidazolylporphyrinatozinc) Molecules

“…The structures formed in the variouss olvents were determined by comparing their UV/Vis spectra with those of 3Zn 2 and 3FbZn in chloroform, in which they form E-and S-dimers, respectively,a sc onfirmed by 1 HNMR analysis. [18] In the UV/Viss pectra,t he characteristic peaks used to identify the E-and S-dimersa ppear at around 720 and 745 nm, respectively (see Figure S3). Because this differencei ss ufficiently large (25 nm) and the respective peaks have characteristic shapes,t he S-dimer (if present) is easily detected.T he UV/Vis spectra presented in Figure S1 indicate that 3Zn 2 forms the E-dimer in all four solvents.…”

“…was close to zero. Equilibrium (16) can be divided into the desolvation of the E-polymer [equilibrium (17)],t he transformation of the E-to the S-polymer in av acuum [equilibrium (18)],a nd the solvation of the Spolymer to give the solvated S-polymer [equilibrium (19)]. Thus, the thermodynamic cycle of the E/S transformation in solution can be described as follows: DG8 (E/S)obs.…”

“…[4d, 17] Recently,w es uccessfully developed as timuli-responsive supramolecular polymer system to detect weak van der Waals interactions between solvents and neutral, nonpolar zinc por-phyrin. [18] In this system,t he interconversion of supramolecular polymers composed of bis(imidazolylporphyrinatozinc) molecules linked through a1 ,3-butadiyne moiety, 1Zn 2 and 2Zn 2 , occurs, depending on the solvents used. For example, they form extended (E) polymer in "good" solvents, such as chloroform (CHCl 3 ), whereas they form stacked (S) polymers in "poor" solvents, such as 1,2-dimethoxyethane (DME), as shown in Figure 1.…”