02517nas a2200205 4500008004100000245015200041210006900193260000800262300001600270490000700286520173400293100002102027700001702048700002302065700002502088700002202113700002402135700002402159856012802183 2017 eng d00aH-Bonding assisted self-assembly of anionic and neutral ligand on metal: a comprehensive strategy to mimic ditopic ligands in olefin polymerization0 aHBonding assisted selfassembly of anionic and neutral ligand on  cOCT a12448-124560 v563 aSelf-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 [{COOC6H4-NH(CO)NH2}{Ph2PC6H4NH(CO)NH2}PdMeDMSO] (4a). The identity of 4a was established by NMR and mass spectroscopy. Along the same lines, 3-(3-phenylureido)benzoic acid (2b) and 1-(3-(diphenylphosphanyl)phenyl)-3-phenylurea (1b) self-assemble on a metal template to produce palladium complex [{COOC6H4NH(CO)NHPh}{Ph2PC6H4NH(CO)NHPh}PdMePy] (5c). The existence of 5c was confirmed by Job plot, 1-2D NMR spectroscopy, deuterium labeling, IR spectroscopy, UV-vis spectroscopy, model complex synthesis, and DFT calculations. These solution and gas phase investigations authenticated the presence of intramolecular hydrogen bonding between hydrogen's of 1b and carbonyl oxygen of 2b. The generality of the supramolecular approach has been validated by preparing six complexes from four monodentate ligands, and their synthetic utility was demonstrated in ethylene polymerization. Complex 4a was found to be the most active, leading to the production of highly branched polyethylene with a molecular weight of 55700 g/mol and melting temperature of 112 degrees C.1 aMote, Nilesh, R.1 aPatel, Ketan1 aShinde, Dinesh, R.1 aGaikwad, Shahaji, R.1 aKoshti, Vijay, S.1 aGonnade, Rajesh, G.1 aChikkali, Samir, H. uhttps://library.ncl.res.in/content/h-bonding-assisted-self-assembly-anionic-and-neutral-ligand-metal-comprehensive-strategy02509nas a2200241 4500008004100000245014200041210006900183260000800252300001400260490000700274520163100281100001701912700002401929700002401953700001601977700001701993700001902010700003502029700002202064700003002086700002402116856012702140 2017 eng d00aSecondary interactions arrest the hemiaminal intermediate to invert the modus operandi of schiff base reaction: a route to benzoxazinones0 aSecondary interactions arrest the hemiaminal intermediate to inv cAPR a4342-43510 v823 aDiscovered by Hugo Schiff, condensation between amine and aldehyde represents one of the most ubiquitous reactions in chemistry. This classical reaction is widely used to manufacture pharmaceuticals and fine chemicals. However, the rapid and reversible formation of Schiff base prohibits formation of alternative products, of which benzoxazinones are an important class. Therefore, manipulating the reactivity of two partners to invert the course of this reaction is an elusive target. Presented here is a synthetic strategy that regulates the sequence of Schiff base reaction via weak secondary interactions. Guided by the computational models, reaction between 2,3,4,5,6-pentafluoro-benzaldehyde with 2-amino-6methylbenzoic acid revealed quantitative (99%) formation of 5-methyl-2-(perfluoropheny01,2-dihydro-4H-benzo[d][1,3]oxazin-4-one (15). Electron donating and electron withdrawing ortho-substituents on 2-aminobenzoic acid resulted in the production of benzoxazinones 936. The mode of action was tracked using low temperature NMR, IN vis spectroscopy, and isotopic (O-18) labeling experiments. These spectroscopic mechanistic investigations revealed that the hemiaminal intermediate is arrested by the hydrogen-bonding motif to yield benzoxazinone. Thus, the mechanistic investigations and DFT calculations categorically rule out the possibility of in situ imine formation followed by ring-closing, but support instead hydrogen-bond assisted ring-closing to prodrugs. This unprecedented reaction represents an interesting and competitive alternative to metal catalyzed and classical methods of preparing benzoxazinone.1 aPatel, Ketan1 aDeshmukh, Satej, S.1 aBodkhe, Dnyaneshwar1 aMane, Manoj1 aVanka, Kumar1 aShinde, Dinesh1 aRajamohanan, Pattuparambil, R.1 aNandi, Shyamapada1 aVaidhyanathan, Ramanathan1 aChikkali, Samir, H. uhttps://library.ncl.res.in/content/secondary-interactions-arrest-hemiaminal-intermediate-invert-modus-operandi-schiff-base02653nas a2200217 4500008004100000022001400041245012000055210006900175260000900244300001400253490000700267520188500274100002302159700001702182700001702199700002702216700001802243700002102261700002402282856012902306 2018 eng d a0024-929700aJudicious reduction of supported Ti catalyst enables access to disentangled ultrahigh molecular weight polyethylene0 aJudicious reduction of supported Ti catalyst enables access to d cJUN  a4541-45520 v513 a

Heterogeneous Ziegler-Natta and homogeneous metallocene catalysts are known to produce ultrahigh molecular weight polyethylene (UHMWPE) in the entangled state. On the other hand, only (two) homogeneous single-site catalysts are reported to yield disentangled UHMWPE (dis-UHMWPE). This disparity between the two types of catalysts and the two states of polyethylene can be bridged if a heterogeneous single-site catalyst that can yield dis-UHMWPE is made accessible. Here, one-pot two-step synthesis of a MgCl2 supported [Ti(OEt)(4)] derived catalyst 1 with a two-stage activation strategy is reported to produce dis-UHMWPE. Second activation of catalyst 1 was performed by adding excess modified methylaluminoxane (MMAO12), and XPS analysis indicated that the catalyst existed in only Ti(III) state at [A1]/[Ti] ratio of 600. Catalyst 1 after second activation with MMAO12 was found to be highly active in ethylene polymerization and produced dis-UHMWPE. Polymerization conditions were tailored to obtain molecular weight (M-w) as high as 13 million g/mol PE. To the best of our knowledge, this is the first time a heterogeneous catalyst (catalyst 1) that displays pseudosingle site nature is able to produce dis-UHMWPE. The thus-prepared nascent polyethylene revealed a melting temperature of 141-144 degrees C, which is a characteristic melting transition for a dis-UHMVVPE. The disentangled state of the nascent PE and its M-w and MVVD were further authenticated by rheological investigations. Isothermal time, sweep oscillatory experiments in linear viscoelastic limit revealed a rapid rise in elastic modulus followed by equilibration to plateau modulus, which are characteristic features of the disentangled state. Thus, a pseudo-singlesite heterogeneous catalyst has been accessed, which upon second activation with excess MMAO12 led to the production of dis-UHMWPE.

1 aGote, Ravindra, P.1 aMandal, Dipa1 aPatel, Ketan1 aChaudhuri, Krishnaroop1 aVinod, C., P.1 aLele, Ashish, K.1 aChikkali, Samir, H. uhttps://library.ncl.res.in/content/judicious-reduction-supported-ti-catalyst-enables-access-disentangled-ultrahigh-molecular02037nas a2200289 4500008004100000022001400041245013000055210006900185260000800254300001400262490000700276520106100283653002601344653003101370653001201401653001401413653001701427100002501444700001701469700002401486700002101510700002701531700002401558700002101582700002401603856012001627 2020 eng d a2192-650600aPalladium-catalyzed insertion of ethylene and 1,1-disubstituted difunctional olefins: an experimental and computational study0 aPalladiumcatalyzed insertion of ethylene and 11disubstituted dif cJUN a1200-12090 v853 a

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 perpendicular to O}PdMe(L)] (P perpendicular to O=kappa(2)-P,O-Ar2PC6H4SO2O with Ar=2-MeOC6H4; L=C2H6OS) and the existence of respective insertion intermediates in moderate yield (up to 37 %) was established. These intermediates were exposed to ethylene and corresponding ethylene-inserted products were isolated and characterized. A careful comparison with three model compounds confirmed ethylene insertion and polymerization. Thus, the combined experimental and computational investigations show that DDO-inserted species can undergo ethylene insertion and polymerization.

10aHomogeneous catalysis10ainsertion copolymerization10aOlefins10aPalladium10aPolyethylene1 aGaikwad, Shahaji, R.1 aPatel, Ketan1 aDeshmukh, Satej, S.1 aMote, Nilesh, R.1 aBirajdar, Rajkumar, S.1 aPandole, Satish, P.1 aChugh, Jeetender1 aChikkali, Samir, H. uhttps://library.ncl.res.in/content/palladium-catalyzed-insertion-ethylene-and-11-disubstituted-difunctional-olefins02005nas a2200229 4500008004100000022001400041245010700055210006900162260000800231300001100239490000800250520119300258653002501451653002401476653002101500653002201521653004101543100001701584700002401601700002501625856012501650 2020 eng d a0079-670000aUltrahigh molecular weight polyethylene: catalysis, structure, properties, processing and applications0 aUltrahigh molecular weight polyethylene catalysis structure prop cOCT a1012900 v1093 a

Ultrahigh molecular weight polyethylene (UHMWPE) belongs to an emerging class of high-performance specialty polymers with a unique set of properties and applications. The field has witnessed many scientific and technological advances in recent years. However, synthesis of UHMWPE is not a trivial exercise and presents several challenges. This review addresses these fundamental challenges and provides an overview of recent developments in the field of UHMWPE. The nature of catalysts, reaction conditions that favor its formation, their physical properties, methods of processing them into products, and their applications are discussed. Recent developments in formation of UHMWPE in a disentangled state by use of appropriate catalysts and reaction conditions are also discussed. This has elicited considerable interest as a means of enabling melt processing of UHMWPE. This review provides a comprehensive source of information and understanding of the multifaceted aspects of UHMWPE with specific reference to chemistry, catalysis, processes for manufacturing, and an analysis of catalyst structure-polymer property relationships. (C) 2020 Elsevier B.V. All rights reserved.

10aCatalysts for UHMWPE10aDisentangled UHMWPE10aEntangled UHMWPE10apolyethylene (PE)10aUltrahigh molecular weight (UHMW) PE1 aPatel, Ketan1 aChikkali, Samir, H.1 aSivaram, Swaminathan uhttps://library.ncl.res.in/content/ultrahigh-molecular-weight-polyethylene-catalysis-structure-properties-processing-and