Ligand isomerism fine-tunes structure and stability in zinc complexes of fused pyrazolopyridines

Fused-ring pyrazoles offer a versatile platform for derivitization to give finely tuned and functional ligands in coordination assemblies. Here, we explore the pyrazolo[4,3-b]pyridine (HL1) and pyrazolo[3,4-c]pyridine (HL2) backbones and their...

Molecular Optimization of Incorporating Pyran Fused Acceptor-Donor-Acceptor Type Acceptors Enables over 15% Efficiency in Organic Solar Cells

A series of acceptor-donor-acceptor type of fused-ring non-fullerene acceptors, FOR-IN, FOR-1F and FOR-2F, were designed and synthesized, featuring with the same pyran-composed backbone and different fluorine substituted 1,1-dicyanomethylene-3-indanone terminals. The...

Efficient, Thermally Stable Poly(3-Hexylthiophene)-Based Organic Solar Cells Achieved by Non-Covalently Fused-Ring Small Molecule Acceptors

Organic solar cells (OSCs) based on poly(3-hexylthiophene) (P3HT) have achieved a significant enhancement of the power conversion efficiency (PCE), mainly driven by the development of non-fullerene small-molecule acceptors. However, their...

Inhibitory Activities of Pyrazolo-Oxazine Heterocyclic Derivatives

Despite several reports and reviews addressing the biological significance of pyrazoles and oxazines, no comprehensive work on the pyrazolo oxazine fused ring system has been published so far.We report all biological evaluations on pyrazolo-oxazine derivatives in this mini-review to provide an avenue for medicinal and pharmacological researchers to conduct further in-depth exploration.

Application of Linear Free Energy Relationships (LFER) to pKaH+ of Benzimidazolium Cations: Chemical Education Perspective

Application of Linear Free Energy Relationships (LFER) to pKaH+ data in water at 25o C of deprotonation of protonated fused ring systems like benzimidazolium cations is carried out in the present work. With a good comparison of the sites of substituents with reference to a functional group in benzene ring and the imidazolium ring, an excellent Hammett correlation is observed for the deprotonation of (pKaH+) of protonated fused ring systems like benzimidazolium cations. For the three substituents OH, MeO and Me at position 4 in the benzimidazole satisfy the correlation with I values. A positive Hammet  values of 1.93 indicates that electron withdrawing substituents facilitate the deprotonation. Under the same conditions a Taft * value of 1.11 is obtained for the deprotonation of 2-substituted-benzimidazolium cations. The available pKaH+ data in 5% aq. ethanol at 30o C of 2-methyl benzimidazolium cations and 2-(hydroxyethyl) benzimidazolium cations also followed Hammett correlation. The lower Hammett  value of 0.89 for 2-(hydroxyethyl) benzimidazolium cation series than that of 1.78 of 2-methyl benzimidazolium cation series is explained in terms of strong intramolecular hydrogen bonding in 2-(hydroxyethyl) benzimidazolium cation which resists the easy deprotonation. Deprotonation of 1-substituted-benzimidazolium cations did not follow Hammett relation.