The manifold applications of ionene-based materials such as hydrogels in daily life, biomedical sciences, and industrial processes are a consequence of their unique physical and chemical properties, which are governed by a judicious balance between multiple non-covalent interactions. However, one of the most critical aspects identified for a broader use of different polyelectrolytes is the need of raising their gelation efficiency. This work focuses on surfactant-free ionene polymers 1−3 containing DABCO and N,N′-(x-phenylene)dibenzamide (x = ortho-/meta-/para-) linkages as model systems to develop a combined computational-experimental approach to improve the hydrogelation through a better understanding of the gelation mechanism. Molecular dynamics simulations of isomeric ionenes 1–3 with explicit water molecules point out remarkable differences in the assembly of the polymeric chains in each case. Interchain regions with high degree of hydration (i.e., polymer···water interactions) and zones dominated by polymer···polymer interactions are evident in the case of ortho- (1) and meta- (2) isomeric ionenes, whereas domains controlled by polymer···polymer interactions are practically inexistent in 3. In excellent agreement, ortho-ionene 1 provides experimentally the best hydrogels with unique features such as thixotropic behavior and dispersion ability for single-walles carbon nanotubes.

Gelatin protein was found to catalyze the aldol reaction between cyclohexanone and different aromatic aldehydes under mild reaction conditions. The aldol additions carried out in DMSO at 37° yielded the addition products with moderate diastereoselectivities favoring the syn isomers. Appropriate control experiments demonstrated the activity of the protein in the aldol reaction. The kinetic study of the model reaction between 4-nitrobenzaldehyde and cyclohexanone established a first-order rate constant k=(7.4±0.5)×10⁻³ h⁻¹. Moreover, the scale-up of the process was successfully achieved at 1-g scale in a yield comparable to that in small scale.

We describe the self-assembly properties of chiral N,N′-disubstituted urea-based organocatalyst 1 that leads to the formation of hierarchical supramolecular gels in organic solvents at low concentrations. The major driving forces for the gelation are hydrogen bonding and π–π interactions according to FTIR and ¹H NMR spectroscopy, as well as quantum-mechanical studies. The gelation scope could be interpreted based on Kamlet–Taft solvatochromic parameters. TEM, SEM, and AFM imaging revealed that a variety of morphologies including helical, laths, porous, and lamellar nanostructures could be obtained by varying the solvent. Experimental gelation tests and computational structural analysis of various structurally related compounds proved the existence of a unique set of molecular interactions and an optimal hydrophilic/hydrophobic balance in 1 that drive the formation of stable gels. Responses to thermal, mechanical, optical, and chemical stimuli, as well as multifunctionality were demonstrated in some model gel materials. Specifically, 1 could be used for the phase-selective gelation of organic solvent/water mixtures. The gel prepared in glycerol was found to be thixotropic and provided a sensitive colorimetric method for the detection of Ag^I ions at millimolar concentrations in aqueous solution. Moreover, the gel matrix obtained in toluene served as a nanoreactor for the Friedel–Crafts alkylation of 1H-indole with trans-β-nitrostyrene.

Electrically conductive adhesive polymers offer many potential advantages relative to SnPb solders, including reduced toxicity, low cost, low processing temperatures, and the ability to make application-specific formulations. Polymers generated from the copper(I)-catalyzed cycloaddition (CuAAC) reaction between multivalent azides and alkynes have previously been identified as strong metal-binding adhesives. Herein we demonstrate that the performance of these materials can be remarkably improved by the incorporation of a flexibility-inducing difunctionalized component and a tertiary amine additive in optimized concentrations. The best formulations were identified by means of rapid adhesion testing of a library of potential candidates by using a custom-built instrument and validated in an American Society for Testing and Materials (ASTM)-standard lap-shear test. Characteristic phase transitions were identified by differential scanning calorimetry (DSC) for adhesives with and without the additives as a function of curing temperature. The incorporation of flexible components was found to more than double the strength of the adhesive. Moreover, the adhesive was made electrically conductive by the inclusion of 20 wt % silver-coated copper flakes and further improved in this regard by the incorporation of multiwalled carbon nanotubes in the formulation.

This work demonstrates that the incorporation of azobenzene residues into the side chain of low-molecular-weight peptides can modulate their self-assembly process in organic solvents leading to the formation of stimuli responsive physical organogels. The major driving forces for the gelation process are hydrogen bonding and π–π interactions, which can be triggered either by thermal or ultrasound external stimuli, affording materials having virtually the same properties. In addition, a predictive model for gelation of polar protic solvent was developed by using Kamlet–Taft solvent parameters and experimental data. The obtained viscoelastic materials exhibited interconnected multistimuli responsive behaviors including thermal-, photo-, chemo- and mechanical responses. All of them displayed thermoreversability with gel-to-sol transition temperatures established between 33–80 °C and gelation times from minutes to several hours. Structure–property relationship studies of a designed peptide library have demonstrated that the presence and position of the azobenzene residue can be operated as a versatile regulator to reduce the critical gelation concentration and enhance both the thermal stability and mechanical strength of the gels, as demonstrated by comparative dynamic rheology. The presence of N-Boc protecting group in the peptides showed also a remarkable effect on the formation and properties of the gels. Despite numerous examples of peptide-based gelators known in the literature, this is the first time in which low-molecular-weight peptides bearing side chain azobenzene units are used for the synthesis of “intelligent” supramolecular organogels. Compared with other approaches, this strategy is advantageous in terms of structural flexibility since it is compatible with a free, unprotected amino terminus and allows placement of the chromophore at any position of the peptide sequence.

Oxalic acid has been proven to be the lowest molecular weight organic ligand able to form robust supramolecular metallogel networks in the presence of metal salts. In particular, two novel multifunctional metallogels were readily prepared at room temperature by simple mixing of stock solutions of Cu^II acetate monohydrate or Cu^II perchlorate hexahydrate and oxalic acid dihydrate. Formation of different polymorphs and unprecedented proton conduction under anhydrous conditions were also demonstrated with some of these materials.