Reduction of Sulfur Dioxide to Sulfur Monoxide by Ferrous Porphyrin**

The reduction of SO₂ to fixed forms of sulfur can address the growing concerns regarding its detrimental effect on health and the environment as well as enable its valorization into valuable chemicals. The naturally occurring heme enzyme sulfite reductase (SiR) is known to reduce SO₂ to H₂S and is an integral part of the global sulfur cycle. However, its action has not yet been mimicked in artificial systems outside of the protein matrix even after several decades of structural elucidation of the enzyme. While the coordination of SO₂ to transition metals is documented, its reduction using molecular catalysts has remained elusive. Herein reduction of SO₂ by iron(II) tetraphenylporphyrin is demonstrated. A combination of spectroscopic data backed up by theoretical calculations indicate that Fe^IITPP reduces SO₂ by 2e⁻/2H⁺ to form an intermediate [Fe^III−SO]⁺ species, also proposed for SiR, which releases SO. The SO obtained from the chemical reduction of SO₂ could be evidenced in the form of a cheletropic adduct of butadiene resulting in an organic sulfoxide.     

Surface morphology and active sites of TiO<Subscript>2</Subscript> for photoassisted catalysis

The main aim of this work is to discriminate the closely related adsorption and catalytic degradation processes that occur during a photocatalytic reaction. Very high-surface-area TiO₂ and Pd-doped TiO₂ were synthesized by microwave-assisted hydrothermal synthesis and used for degradation of methylene blue as a model pollutant dye. Thorough structural, morphological, and surface analyses of the synthesized catalysts were conducted to investigate key material properties that influence adsorption and catalytic performance. The adsorption capacity of the catalysts was determined by fitting adsorption data using the Langmuir isotherm model, and the photocatalytic activity of the synthesized samples was evaluated by periodically measuring the concentration of methylene blue as it was photocatalytically degraded under ultraviolet (UV) light. The results indicated that noble-metal incorporation compromised adsorption but favored catalytic performance.     

Highly regioselective ring opening of epoxides and aziridines using (bromodimethyl)sulfonium bromide

Epoxides and aziridines undergo ring opening efficiently with (bromodimethyl)sulfonium bromide at room temperature to form the corresponding β-bromohydrins and β-bromoamines, respectively. The conversions are highly regioselective and afford the products in excellent yields within a short period of time.     

Vanadium(III) Chloride (VCl3): Efficient Reagent for the Introduction of Tetrahydrofuran‐Based Acetal Protecting Groups for Alcohols

Treatment of different types of alcohols with tetrahydrofuran (THF) in the presence of VCl₃ and CCl₄ smoothly afforded the corresponding THF‐based acetals in excellent yields. The reaction is fast at room temperature, and several functional groups are tolerated, with no racemization being observed. A radical mechanism, based on Cl₃C^. as the active species, is proposed for this novel kind of transformation, which complements the classical tetrahydro‐2H‐pyran‐2‐yl (THP) protocol.     

A promising class of luminescent derivatives of Silver(I) and Gold(I)-N-heterocyclic carbene

Starting from proligand 1-methyl-2-(phenyl)imidazo[1,5-a]pyridine-2-iumchloride ( 1 .HCl), 1-methyl-2-(phenyl)imidazo[1,5-a]pyridine silver(I)chloride, ( 2 ) has been prepared. Synthesis, structures and photophysical properties of (2,2^/−bipyridyl)-1-methyl-2-(phenyl)imidazo[1,5-a]pyridinesilver(I)hexaflurophosphate, ( 3 ), 1-methyl-2-(phenyl)imidazo[1,5-a]pyridinesilver(I)carbazolate, ( 4 ) and 1-methyl-2-(phenyl)imidazo[1,5-a]pyridinegold(I)carbazolate, ( 5 ) are focused. Herein we have first reported the NHC-Ag-(bpy/carbazole). All the complexes have been characterized by elemental analysis, various spectroscopic studies and finally screened for luminescent properties. All the complexes are strongly emissive. Solid state structures of 2 , 3 , 4 and 5 have been determined by X-ray diffraction studies. Conventionally, complex 2 adopts linear geometry whereas complex 3 embraces triangular planar geometry around Ag; complex 4 and 5 clinches linear geometry around Ag/Au. All the complexes absorb light within 275–343 nm. Complex 3 is luminous at ~407 mn, whereas complex 4 and 5 luminous at ~360 nm having short life time 1.00–6.97 ns. The quantum yield (Φ_em) of the complexes varies 0.106–0.186. It is expected variation of luminescence arises due to change of metal and the chromophore (bpy/carbazole). Density Functional Theory (DFT) and Temparature Dependent Density Functional Theory (TDDFT) calculations were performed to verify crystallographically derived parameters and to calculate the UV–Vis properties of the ground state as well as of the first excited state of the complexes.     

Lipase Catalyzed Regioselective Deacetylation of Tetraacetylginkgetin

Lipase (Amano PS) catalyzed regioselective deacetylation of tetraacetylginkgetin has been reported.     

Stereoselective total synthesis of dodoneine

The stereoselective total synthesis of the naturally occurring bioactive dihydropyranone dodoneine has been achieved involving the Sharpless asymmetric epoxidation, 1,3-syn diastereoselective reduction and Grubb’s ring-closing metathesis as key steps.     

Controlled Release of an Antihypertensive Drug through Interpenetrating Polymer Network Hydrogel Tablets of Tamarind Seed Polysaccharide and Sodium Alginate

The application of interpenetrating polymer network (IPN) hydrogel tablets of tamarind seed polysaccharide and sodium alginate for controlled release of a water-soluble antihypertensive drug, propranolol HCl (PPL), was investigated. The IPN tablets loaded with PPL or PPL–resin complex (resinate) were prepared by a wet granulation/covalent cross-linking method. Fourier Transform Infrared Spectroscopic confirmed the cross-linking reaction and IPN formation, while X-ray Diffraction and Scanning Electron Microscopy studies confirmed the amorphous dispersion of the drug within the IPN tablets. The plain drug PPL showed complete release within 1 h, while drug release from the resinate was prolonged for 2.5 h and the IPN matrices showed drug release up to 24 h. The drug release rate from the IPN matrices was affected by polymer concentration and cross-linking time; the higher the cross-linking time, the slower was the drug release. The drug release mechanism was found to be of a non-Fickian type.