Investigating the Influence of Aromatic Counterions on the Micellar Structure and Aggregation Behavior of Morpholinium-Based Surface-Active Ionic Liquids in an Aqueous Solution.

Two morpholinium-based surface-active ionic liquids (SAILs) with aromatic counterions were synthesized, namely, n-dodecyl-n-methylmorpholinium salicylate [C12mmor][Sal] and n-dodecyl-n-methylmorpholinium 3-hydroxy-2-naphthoate [C12mmor][3-h-2-n], and explored their aggregation behavior in aqueous solutions systematically. Electrical conductivity, small-angle neutron scattering (SANS), surface tension (ST), and UV-vis spectroscopy measurements were employed to determine various thermodynamic, micellar, and interfacial parameters, like the degree of counterion binding (ß), critical micelle concentration (CMC), minimum area per molecule (Amin), surface excess concentration (Γmax), standard Gibbs free energy of adsorption (ΔGad0), aggregation number (Nagg), standard Gibbs free energy of micellization (ΔGm0), standard enthalpy of micelle formation (ΔHm0), and the standard entropy of micellization (ΔSm0) in an aqueous solution. Incorporating the aromatic counterions favors significantly excellent micellization properties over conventional halogenated SAILs such as [C12mmor][Br]. SANS analysis revealed that upon changing the counterion from salicylate to 3-hydroxy-2-naphthoate, the structure changed from prolate ellipsoidal micelles to large unilamellar vesicles. Also, increasing the concentration in the case of [C12mmor][Sal] resulted in a lower aggregation number.

Synthesis, Self-Aggregation, Surface Characteristics, Electrochemical Property, Micelle Size, and Antimicrobial Activity of a Halogen-Free Picoline-Based Surface-Active Ionic Liquid.

We present a new approach toward the design of a halogen-free picoline-based surface-active ionic liquid (SAIL) (1-octyl-4-methyl pyridinium dodecyl sulfate) [C8γPic]DS consisting of long dodecyl sulfate (DS) as an anion. The surface properties, micellization behavior, and antimicrobial activity in an aqueous solution were investigated using tensiometry, conductometry, and ultraviolet (UV) spectroscopy. Incorporating the DS group in SAIL leads to lower critical micellar concentration (CMC) and enhanced adsorption at the air/water interface of the functionalized ionic liquid compared to the C8-alkyl chain-substituted pyridine ionic liquids. The antimicrobial activity was evaluated against a representative Gram-negative and Gram-positive bacteria panel. Antibacterial activities increased with the alkyl chain length, C8 being the homologous most effective antimicrobial agent. The micelle size of [C8γPic]DS was determined by the dynamic light-scattering (DLS) study. Cyclic voltammetry (CV) measurements have been employed to evaluate the interaction between the SAIL micelle and working electrode, diffusion coefficient, and micelle size of the SAIL solution. The diffusion coefficient explored the correlation of surface properties and the antimicrobial activity of [C8γPic]DS. This halogen-free SAIL is the future of wetting agents and emulsion studies in agriculture due to its small micelle size and surface characteristics.

Immobilization of Agrobacterium tumefaciensd-psicose 3-epimerase onto titanium dioxide for bioconversion of rare sugar.

d-Psicose (d-ribo-2-hexulose or d-allulose) is the Carbon-3 epimer of d-fructose sugar and considered as an unnatural (rare) sugar found in low amount in nature. It has about 70% of the relative sweetness but 0.3% of the energy of sucrose, which is suggested as the most suitable sucrose substitute for food additives. Enzymatic biosynthesis using ketose 3-epimerases is a necessary procedure for the production of d-Psicose from d-fructose. However, significant drawbacks in the application of ketose 3-epimerases at industrial scale observe lower thermal stability as well as bioconversion efficiency, reusability and recovery of the enzyme. We have attempted immobilization of ketose 3-epimerases from Agrobacterium tumefaciens (agtu) d-psicose 3-epimerase (DPEase) on titanium dioxide. Further, Scanning electron microscopy (SEM), inverted microscopy, Fourier transform infrared spectroscopy (FTIR) and UV-vis spectroscopy showed that the enzyme was successfully immobilized on the titanium dioxide (TiO2) surface. Titanium dioxide immobilized agtu-DPEase (TiO2-agtu-DPEase) shows pH optima at 6.0 and 60 °C as a higher working temperature. TiO2-agtu-DPEase showed a half-life of 180 min at 60 °C, which is higher as compared to Agrobacterium tumefaciens (agtu) DPEase (3.99 min at 50 °C). At equilibrium, 36:64 (D-psicose: d-fructose), the bioconversion efficiency was accounted for titanium dioxide immobilized DPEase, which is higher than the agtu-DPEase. Titanium dioxide immobilized DPEase showed bioconversion efficiency up to 9 cycles of reusability.

Above 800 mV Open-Circuit Voltage in Solid-State Photovoltaic Devices Using Phosphonium Cation-Based Solid Ionic Conductors.

Here, we report phosphonium-based two solid ionic conductors (SICs), namely, triphenylphosphonium methyl iodide (TPPMeI) and triphenylphosphonium iodide (TPPHI), prepared via simple protocol at room temperature and were used as an electrolyte for solid-state photovoltaic devices (ss-PVDs) with open-circuit voltage (Voc) exceeding 800 mV. Here, for the first time, detailed electrochemical investigations with theoretical aspects of phosphonium electrolytes were conducted, where PVDs prepared from these SICs, TPPMeI, showed the highest power conversion efficiency (PCE) of 4.08% with a Voc of 810 mV. However, this performance was further improved up to the PCE of 6.71% with 824 mV of Voc in the presence of additives like LiI and tert-butyl pyridine. This work leads to find the best alternative of liquid and quaternary ammonium ion-based electrolytes that suffers from problems like lower Voc (<800 mV) and stability, leakage, etc.