Kinetic and Morphological Studies of Two Different Topological Structures Developed from <i>N, N</i>’-Bis (4-N-Alkylo-Xybenzoyl) Hydrazine (4D₁₆) Organogel

<div><p>The compound <i>N</i>, <i>N</i>’-bis (4-n-alkylo-xybenzoyl) hydrazine (4D₁₆), containing a dihydrazide unit in the rigid core, had been systematically investigated in view of their gelation behaviors, topological structures, and gelation formation processes. It has been demonstrated that 4D₁₆ shows strong gelation ability in nonpolar solvents such as benzene and toluene. The xerogels consist of entangled ribbons with the width about 5 μm. According to X-ray diffraction (XRD), cubic structure is revealed in the benzene system, whereas layered structure is observed in toluene system. The morphological observations and kinetic studies by fluorescence spectroscopy as well as rheological study further reveal that self-assembly processes during gelation also differs. Radius fibers with a fractal dimension about 1.4 were observed in benzene system; whereas, less open fibrillar structures with fractal dimension approximately 1.1 were revealed for toluene system. The present results appear to represent that the molecular packing modes turn out to be solvent-dependent, which is due to unique dynamic processes.</p></div

Supporting information is located at step 6--file unload from Exploring the difference in xerogels and organogels through <i>in situ</i> observation

FT-IR, Raman, PL spectra, DSC and XRD of TC6 from DCE, 1H NMR, Absorption, PL spectra and DSC in EtO

Substituent Effect on Intramolecular Charge Transfer of Symmetric Methoxy-Substituted Bi-1,3,4-oxadiazole Derivatives

Intramolecular charge-transfer characteristics of a series symmetric methoxy -substituted bi-1,3,4-oxadiazole derivatives with various substituted positions and quantities have been studied with a combination of experimental techniques and theoretical calculations to investigate the substituent effect. Different degrees of fluorescence red shift in polar solvents are observed in these compounds. The meta-substituted molecule (BOXD-<i>m</i>-OCH₃) exhibits a larger red shift (82 nm) than the other two monosubstituted molecules, BOXD-<i>o</i>-OCH₃ (40 nm) and BOXD-<i>p</i>-OCH₃ (37 nm); the polysubstituted molecules BOXD-D1 and BOXD-T1 show 80 and 104 nm red shifts, respectively, which are obviously larger than the monosubstituted molecules. The changes of molecular dipole moment between the ground state and charge transfer (CT) excited state are calculated to be on the same order with the degree of red shift (7.56 D in BOXD-<i>o</i>-OCH₃, 12.07 D in BOXD-<i>m</i>-OCH₃, 7.38 D in BOXD-<i>p</i>-OCH₃, 14.79 D in BOXD-D1, and 16.80 D in BOXD-T1). Theoretical calculations at the density functional theory level reveal that the first singlet excited state of all of these compounds shows both π–π* and CT characteristics and the charge has been proven to transfer from the terminal methoxy phenyl group to the central bioxadiazole group. The analysis of charge transfer based on electron density shows that the greater the amount substituent, the more charge would be involved in the intramolecular charge transfer. In addition, the negative barycenter has a tendency to locate close to the methoxy substituent, which would cause the difference in the charge-transferred distance. The transferred charge and CT distance work jointly and finally lead to differences in dipole moment variation. These findings could provide very good guidance for the design of molecules with intramolecular charge-transfer characteristics

Gelation behavior and structure transition in mixtures of disc-shape dihydrazide derivative

<p>Gelation behavior in mixtures has been investigated based on a gelator (BP8-A), containing three di-hydrazide units as the rigid core. It was demonstrated that BP8-A was soluble in many organic solvents, such as chloroform (CHL), benzene (Ben), toluene (Tol), and tetrahydrofuran (THF) but formed gels in alcohols, except methanol (MeOH) in which precipitate was observed. We developed a simple but effective method for preparation of BP8-A gel in different solvents at room temperature without heating-cooling process, that is, injection of certain amount of methanol (volume ratio between 8:2 and 7:3) into BP8-A solutions in CHL, Ben, Tol, and THF. Xerogels from MeOH/CHL, MeOH/Ben, MeOH/Tol, and MeOH/THF showed crystalline feature. The films from BP8-A xerogels in the mixtures are superhydrophobic with the contact angles (CAs) higher than 140°.</p