COVID-19 and Progressive Orthodontics.

Introduction: The coronavirus disease (COVID-19) was declared as a pandemic by the World Health Organization on 30th January 2020 so the practice of dentistry and orthodontics has come to a standstill.

Description: The COVID-19 affects different people in different ways. The most common symptoms resemble very much to that of seasonal flu.

COVID-19 and orthodontic treatment: current perspectives.

Introduction: A pandemic was declared by the World Health Organization on 30th January 2020, the coronavirus disease (COVID-19) emerged, and led to standstill of Dentistry and Orthodontics.

Description: The COVID-19 is a very multivariant disease. It affects in many different ways; the most reported symptoms resemble very much to that of a seasonal flu.

Controlled di-lithiation enabled synthesis of phosphine-sulfonamide ligands and implications in ethylene oligomerization.

Catalyst design for ethylene oligomerization has attracted significant interest. Herein, we report the synthesis of phosphine-sulfonamide-derived palladium complexes and examine their performance in ethylene oligomerization. Arresting a dilithiation intermediate of N-(2-bromophenyl)-4-methylbenzenesulfonamide (1) at -84 °C selectively produced N-(2-(bis(2-methoxyphenyl)phosphanyl)phenyl)-4-methylbenzenesulfonamide (L1A).

Palladium-Catalyzed Insertion of Ethylene and 1,1-Disubstituted Difunctional Olefins: An Experimental and Computational Study.

Insertion or coordination copolymerization of ethylene with di-substituted olefins is challenging and the choice of di-substituted mono-functional olefin versus di-substituted di-functional olefin (DDO) appears to be decisive. Here we show that DDO-inserted species are amenable to ethylene insertion and polymerization. DDOs such as 2-acetamidoacrylic acid (AAA), methyl 2-acetamidoacrylate (MAAA), and ethyl 2-cyanoacrylate (ECA) were treated with palladium complex [{P∧O}PdMe(L)] (P∧O=κ -P,O-Ar PC H SO O with Ar=2-MeOC H ; L=C H OS) and the existence of respective insertion intermediates in moderate yield (up to 37 %) was established.

Neutral Imino-Methyl Benzenesulfonate-Ligated Pd(II) Complexes and Implications in Ethylene Polymerization.

A reaction between sodium 2-formylbenzenesulfonate and aniline revealed the near-quantitative (91%) formation of sodium-2-((phenylimino)methyl)benzenesulfonate . The identity of was unambiguously ascertained using spectroscopic and analytical methods. The scope of this methodology was widened and various electron-donating amines were treated with sodium 2-formylbenzenesulfonate, and a small library of 6 imine ligands was generated.

Hydrogen-Bonding-Assisted Supramolecular Metal Catalysis.

The process of catalyst screening and discovery still largely relies on traditional ligand-design approaches, which suffer from complex synthetic requirements and offer limited structural diversity. On the contrary, supramolecular chemistry offers the potential to harness multiple weak secondary interactions to deliver self-assembled catalysts with diverse structures or to orient substrates to achieve enzyme-like activity and selectivity. Herein, the application of hydrogen-bonding (H-bonding) interactions as a construction element and directing group in "supramolecular transition-metal catalysis" is critically reviewed and the current state-of-the-art in the field is presented.

H-Bonding Assisted Self-Assembly of Anionic and Neutral Ligand on Metal: A Comprehensive Strategy To Mimic Ditopic Ligands in Olefin Polymerization.

Self-assembly of two neutral ligands on a metal to mimic bidentate ligand coordination has been frequently encountered in the recent past, but self-assembly of an anionic ligand on a metal template alongside a neutral ligand remains an elusive target. Such a self-assembly is hampered by additional complexity, wherein a highly negatively charged anion can form intermolecular hydrogen bonding with the supramolecular motif, leaving no scope for self-assembly with neutral ligand. Presented here is the self-association of anionic ligand 3-ureidobenzoic acid (2a) and neutral ligand 1-(3-(diphenylphosphanyl)phenyl)urea (1a) on a metal template to yield metal complex [{COOCHNH(CO)NH}{PhPCHNH(CO)NH}PdMeDMSO] (4a).

Efficacy of planas direct tracks for early treatment of skeletal Class II malocclusion--a clinical and cephalometric study.

Objective: To evaluate the efficacy of Planas Direct Tracks in the treatment of skeletal Class II malocclusion due to retrognathic mandible in the intermediate mixed dentition stage clinically and cephalometrically.

Materials And Method: A six month cross sectional comparative study consisted of 40 subjects (21 males and 19 females) with a mean age of 9.8 + 1.