1-Phenyldiazenyl-8-Phenylhydrazononaphthalene-7(8H)-One-2-ol: Co-Existence of Azo-Hydroxy and Hydrazo-Keto Forms

Abstract  

The compound crystallizes in the triclinic P[`1] P\bar{1} space group and unit cell dimensions of a = 8.158 ?, b = 12.490 ?, c = 17.129 ?; α = 93.24°, β = 94.72°, γ = 97.61° and Z = 4. The structure was solved by direct methods and refined to an R1 value of 0.0890 on 2,278 observed reflections. There are two molecules in the asymmetric residue unit of the compound. In the title compound C₂₂H₁₆N₄O₂, two diazene groups at C1 and C8 and two hydroxy groups at C2 and C7 bring into play a unique azo-hydrazo equilibrium in which azo-hydroxy and hydrazo-keto forms co-exist in the molecule. The hydrazone H atom and the keto O atom are linked by an intramolecular N–H···O hydrogen bond on the other hand the hydroxy H atom and the azo N atom are linked by two intramolecular O–H···N hydrogen bonds.     

Photocatalytic Au–Bi2S3 Heteronanostructures

Au–Bi₂S₃ heteronanostructure photocatalysts were designed in which the coupling of a metal plasmon and a semiconductor exciton aids the absorption of solar light, enhances charge separation, and results in improved catalytic activity. Furthermore, these nanostructures show a unique pattern of structural combination, with Au nanoparticles positioned at the center of Bi₂S₃ nanorods. The chemistry of formation of these nanostructures, their epitaxy at the junction, and their photoconductance were studied, as well as their photoresponse properties.     

Synthesis and evaluation of structural requirements for antifungal activity of cyrmenin B1 analogues

In a study aiming to define the structural elements essential to cyrmenin B₁ antifungal activity, the synthesis of a series of analogues was carried out. The structural modification introduced stepwise in distinct areas of the parent molecule allowed a deeper insight to be gained into the most relevant structural features affecting the activity of the natural compound. The bioassay results clearly indicate the relevance of each portion of the parent molecule, only the modification of the conjugated double bond geometry being tolerated.     

Organoboron Compounds: Effective Antibacterial and Antiparasitic Agents

The unique electron deficiency and coordination property of boron led to a wide range of applications in chemistry, energy research, materials science and the life sciences. The use of boron-containing compounds as pharmaceutical agents has a long history, and recent developments have produced encouraging strides. Boron agents have been used for both radiotherapy and chemotherapy. In radiotherapy, boron neutron capture therapy (BNCT) has been investigated to treat various types of tumors, such as glioblastoma multiforme (GBM) of brain, head and neck tumors, etc. Boron agents playing essential roles in such treatments and other well-established areas have been discussed elsewhere. Organoboron compounds used to treat various diseases besides tumor treatments through BNCT technology have also marked an important milestone. Following the clinical introduction of bortezomib as an anti-cancer agent, benzoxaborole drugs, tavaborole and crisaborole, have been approved for clinical use in the treatments of onychomycosis and atopic dermatitis. Some heterocyclic organoboron compounds represent potentially promising candidates for anti-infective drugs. This review highlights the clinical applications and perspectives of organoboron compounds with the natural boron atoms in disease treatments without neutron irradiation. The main topic focuses on the therapeutic applications of organoboron compounds in the diseases of tuberculosis and antifungal activity, malaria, neglected tropical diseases and cryptosporidiosis and toxoplasmosis.     

Autoresolution of Segregated and Mixed p‐n Stacks by Stereoselective Supramolecular Polymerization in Solution

A “chirality driven self‐sorting” strategy is introduced for the controlled supramolecular organization of donor (D) and acceptor (A) molecules in multicomponent assemblies. The trans‐1,2‐bis(amido)cyclohexane (trans‐BAC) has been identified as a supramolecular motif with strong homochiral recognition to direct this chirality controlled assembly process of enantiomers in solution. Stereoselective supramolecular polymerization of trans‐BAC appended naphthalene diimide monomers (NDIs) has been probed in detail by spectroscopic and mechanistic investigations. This chirality‐driven self‐sorting design of enantiomeric components also offers to realize mixed and segregated D‐A stacks by supramolecular co‐assembly of the NDI acceptors with trans‐BAC appended dialkoxynaphthalene (DAN) donor monomers. Such an unprecedented chirality control on D‐A organization paves the way for the creation of supramolecular p‐n nanostructures with controlled molecular‐level organization.     

Natural convection flow over a vertical frustum of a cone for constant wall heat flux

Laminar natural convection flow and heat transfer over a vertical frustum of a cone has been studied. The governing boundary layer equations are solved using local non-similarity method for constant wall heat flux. The local similarity and the local non-similarity two and three-equation models are constructed and the resulting equations are solved numerically. Results obtained from two and three-equation models are in good agreement. The numerical values of the flow and temperature functions required to calculate the surface skin friction and heat transfer rate are reported for various values of Prandtl numbers.     

Total Synthesis of Δ12‐Prostaglandin J3, a Highly Potent and Selective Antileukemic Agent

A catalytic asymmetric total synthesis of the potent and selective antileukemic Δ¹²‐prostaglandin J₃ (Δ¹²‐PGJ₃) is described. The convergent synthesis proceeded through intermediates 2 and 3 , formed enantioselectively from readily available starting materials and coupled through an aldol reaction followed by dehydration to afford stereoselectively the cyclopentenone alkylidene structural motif of the molecule.