1. Surface Plasmon Resonance Sensitivity Enhancement Based on Protonated Polyaniline Films Doped by Aluminum Nitrate
Qais M Al-Bataineh, Victoria Shpacovitch, Diyar Sadiq, Ahmad Telfah, Roland Hergenröder Biosensors (Basel). 2022 Dec 3;12(12):1122. doi: 10.3390/bios12121122.
Complex composite films based on polyaniline (PANI) doped hydrochloric acid (HCl) incorporated with aluminum nitrate (Al(NO3)3) on Au-layer were designed and synthesized as a surface plasmon resonance (SPR) sensing device. The physicochemical properties of (PANI-HCl)/Al(NO3)3 complex composite films were studied for various Al(NO3)3 concentrations (0, 2, 4, 8, 16, and 32 wt.%). The refractive index of the (PANI-HCl)/Al(NO3)3 complex composite films increased continuously as Al(NO3)3 concentrations increased. The electrical conductivity values increased from 5.10 µS/cm to 10.00 µS/cm as Al(NO3)3 concentration increased to 32 wt.%. The sensitivity of the SPR sensing device was investigated using a theoretical approach and experimental measurements. The theoretical system of SPR measurement confirmed that increasing Al(NO3)3 in (PANI-HCl)/Al(NO3)3 complex composite films enhanced the sensitivity from about 114.5 [Deg/RIU] for Au-layer to 159.0 [Deg/RIU] for Au-((PANI-HCl)/Al(NO3)3 (32 wt.%)). In addition, the signal-to-noise ratio for Au-layer was 3.95, which increased after coating by (PANI-HCl)/Al(NO3)3 (32 wt.%) complex composite layer to 8.82. Finally, we conclude that coating Au-layer by (PANI-HCl)/Al(NO3)3 complex composite films enhances the sensitivity of the SPR sensing device.
2. Systematic Study of Regioselective Reductive Ring-Opening Reactions of 4,6- O-Halobenzylidene Acetals of Glucopyranosides
Erika Mezö, Mihály Herczeg, Fruzsina Demeter, Ilona Bereczki, Magdolna Csávás, Anikó Borbás J Org Chem. 2021 Sep 17;86(18):12973-12987. doi: 10.1021/acs.joc.1c01667. Epub 2021 Sep 3.
Reductive openings of cyclic acetals are widely used in modern synthetic organic chemistry for the regioselective introduction of protecting groups. A systematic study was performed on the applicability and efficacy of various hydride donor and protic or Lewis acid reagent combinations in the reductive ring opening of glucosidic 4,6-halobenzylidene acetals bearing an ortho-, meta-, and para-chloro- or -bromo substituent on the benzene ring. Most of the reagent combinations tested cleaved the 4,6-O-halobenzylidene acetal rings at O4 or O6 efficiently and with the expected regioselectivity. The LiAlH4-AlCl3 and the BH3·THF-TMSOTf combinations produced the 4-O-halobenzyl ether/6-OH products with complete regioselectivity and high yields. The use of Me3N·BH3-AlCl3 reagent system in toluene was also effective in cleaving the acetal ring at O6 but was accompanied by Al-chelation-assisted debenzylation side reactions. The NaCNBH3-HCl and the Et3SiH-BF3·Et2O combinations were highly effective in yielding the 6-halobenzyl ether/4-OH derivatives. Et3SiH, in combination with TfOH, produced the 6-O-ether/4-OH products in rapid reactions but also triggered silylation and reductive halobenzylation as secondary transformations. Reductive opening of the 1,3-dioxane ring of pyranosidic 4,6-O-halobenzylidene acetals by the proper reagent combination was found to be an efficient method for the regioselective introduction of versatile halobenzyl protecting groups onto the pyranose ring.
3. Reversible photo control of proton chemistry
Yi Liao Phys Chem Chem Phys. 2022 Feb 16;24(7):4116-4124. doi: 10.1039/d1cp05627a.
Spatial, temporal, and remote control of proton chemistry can be achieved by using photoacids, which are molecules that transform from weak to strong acids under light. Most of proton chemistry is driven by a high concentration of protons ([H+]), which is difficult to obtain using excited-state photoacids. Metastable-stable state photoacids (mPAHs) can reversibly generate a high [H+] under visible light with a moderate intensity. It has been widely applied in different fields, e.g. fueling dissipative assemblies, driving molecular machines, controlling organic reactions, powering nanoreactors, curing diseases, manipulating DNA and proteins, developing smart materials, capturing carbon dioxide in air etc. This article compares mPAH with excited-state photoacid as well as common acids e.g. HCl to explain its advantages. Recent studies on the thermal dynamics, kinetics, and photoreaction of mPAHs are reported. The advantages and disadvantages of the three types of mPAHs, i.e. merocyanine, indazole, and TCF mPAHs, are compared with regard to photo-induced [H+], switching rate, and other properties. The mechanisms of controlling or driving functional systems, which involve acid-base reactions, acid catalyzed reactions, ionic bonding, coordination bonding, hydrogen bonding, ion exchange, cation-π interaction, solubility, swellability, permeability, and pH change in biosystems, are described. Applications of mPAHs in the chemical, material, energy, biotechnology and biomedical fields published in the past 5 years are reviewed. Prospects in the development and application of mPAHs are discussed.
