Proton-Conducting Polymeric Membranes Based on 1,2,4-Triazole

Triazole-rich 3D metal-organic framework incorporated solid electrolytes for superior proton conductivity and durability in fuel cells

Insufficient proton conductivity and oxidative stability of sulfonated hydrocarbons hinder their applicability as proton exchange membrane electrolytes in fuel cells. In this regard, fabrication of proton conducting mixed-matrix membranes (PC-MMMs) can be a superior approach to obtain desirable properties. In this work, a triazole ligand (1H-1,2,4 triazole) was coordinated to a zinc metal node to create a 3D metal-organic framework (MOF) and incorporated as an additive in a sulfonated poly(ether ether ketone) matrix at 1, 3, and 5 weight percentage to fabricate PC-MMMs by the casting process. Several characterization tools such as electrochemical impedance spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy were used to characterise these membranes and study their potential application as electrolyte(s) in PEMFCs (proton exchange membrane fuel cells). Membranes were also tested for water uptake, ion-exchange capacity and oxidative stability in Fenton's reagent. The performance of the polymeric composite membrane containing a 3 wt% MOF was then assessed in a H2/O2 single cell as it demonstrated the highest proton conductivity of 0.04 S cm-1 among all the compositions and a maximum current density of 1191 mA cm-2. The membrane was also subjected to an OCV hold test for 12 hours to study the chemical durability over a period of time. This report establishes that the inclusion of a triazole based MOF enhances the proton conductivity, performance, and thermal and chemical durability of composite membranes which can be considered as a promising electrolyte material at intermediate temperatures after a proper optimisation of different cell parameters.

Exploration of nonlinear optical properties of 4-methyl-4H-1,2,4-triazol-3-yl)thio)-N-phenylpropanamide based derivatives: experimental and DFT approach

Triazoles, nitrogen-containing heterocycles, have gained attention for their applications in medicinal chemistry, drug discovery, agrochemicals, and material sciences. In the current study, we synthesized novel derivatives of N-substituted 2-((5-(3-bromophenyl)-4-methyl-4H-1,2,4-triazol-3-yl)thio)-N-phenylpropanamide and conducted a comprehensive investigation using density functional theory (DFT). These novel structural hybrids of 1,2,4-triazole were synthesized through the multi-step chemical modifications of 3-bromobenzoic acid (1). Initially, compound 1 was converted into its methyl-3-bromobenzoate (2) which was then transformed into 3-bromobenzohydrazide (3). The final step involved the cyclization of compound 3, producing its 1,2,4-triazole derivative (4). This intermediate was then coupled with different electrophiles, resulting in the formation of the final derivatives (7a-7c). Additionally, the characterization of these triazole-based compounds (7a, 7b, and 7c) were carried out using techniques such as IR, HNMR, and UV-visible spectroscopy to understand their structural and spectroscopic properties. The DFT study utilized M06/6-311G(d,p) functional to investigate geometrical parameters, HOMO-LUMO energies, natural bond orbital analyses, transition density matrix (TDM), density of states, and nonlinear optical (NLO) properties. The FMO analysis revealed that compound 7c exhibited the lowest band gap value (4.618 eV). Notably, compound 7c exhibited significant linear polarizability (4.195 >  × 10-23) and first and second hyperpolarizabilities (6.317 >  × 10-30, 4.314 × 10-35), signifying its potential for nonlinear optical applications. These NLO characteristics imply that each of our compounds, especially 7c, plays a crucial part in fabricating materials showing promising NLO properties for optoelectronic applications.

Anhydrous proton conductor consisting of protamine-monododecyl phosphate composite with self-assembled structure

We prepared a protamine-monododecyl phosphate composite by mixing protamine (P) and a monododecyl phosphate (MDP). This P-MDP composite formed an acid-base complex by the electrostatic interaction between cationic protamine and the negatively charged phosphate group. Additionally, according to the X-ray diffraction (XRD) measurements, the composite formed a self-assembled lamellar structure with an interaction between the long alkyl chains of MDP. As a result, the P-MDP composite showed the proton conductivity of 9.5 × 10-4 S cm-1 at 120-130 °C under anhydrous conditions. Furthermore, the activation energy of the proton conduction of the P-MDP composite was approximately 0.18 eV. These results suggested that the proton conduction of the P-MDP composite was based on an anhydrous proton conductive mechanism. In contrast, the anhydrous proton conduction of the P-methanediphosphonic acid (MP) composite, which did not form the self-assembled lamellar structure, was ca. 3 × 10-5 S cm-1 at 120-130 °C and this value was one order of magnitude lower than that of the P-MDP composite. Therefore, the two-dimensional self-assembled proton conductive pathway of the P-MDP composite plays a role in the anhydrous proton conduction.

Composite Hydrogels Based on Bacterial Cellulose and Poly-1-vinyl-1,2,4-triazole/Phosphoric Acid: Supramolecular Structure as Studied by Small Angle Scattering

New composite hydrogels (CH) based on bacterial cellulose (BC) and poly-1-vinyl-1,2,4-triazole (PVT) doped with orthophosphoric acid (oPA), presenting interpenetrating polymeric networks (IPN), have been synthesized. The mesoscopic study of the supramolecular structure (SMS) of both native cellulose, produced by the strain Komagataeibacter rhaeticus, and the CH based on BC and containing PVT/oPA complex were carried out in a wide range of momentum transfer using ultra- and classical small-angle neutron scattering techniques. The two SMS hierarchical levels were revealed from 1.6 nm to 2.5 μm for the objects under investigation. In addition, it was shown that the native BC had a correlation peak on the small-angle scattering curves at 0.00124 Å-1, with the correlation length ξ being equal to ca. 510 nm. This motive was also retained in the IPN. The data obtained allowed the estimation of the fractal dimensions and ranges of self-similarity and gave new information about the BC mesostructure and its CH. Furthermore, we revealed them to be in coincidence with Brown's BC model, which was earlier supported by Fink's results.