02254nas a2200277 4500008004100000022001400041245011700055210006900172260000900241300001100250490000800261520133500269653001201604653002701616653002901643653002001672653002301692100001701715700002201732700001801754700002001772700001901792700001901811700002101830856012501851 2022 eng d a0167-732200aElliptically birefringent chemically tuned liquid crystalline nanocellulose composites for photonic applications0 aElliptically birefringent chemically tuned liquid crystalline na cNOV  a1203260 v3663 a

Cellulose nanocrystals (CNCs) based photonic materials are one of the promising materials in the recent trends. The liquid crystalline behavior of the CNCs can be tailored to different advanced applications. The proposed research investigates the potential of CNCs as an optically active material. CNCs were tuned to hydroxypropyl nano cellulose (HPNC) with the degree of substitution 1.39. The prepared liquid crystalline HPNC were dispersed in various concentrations of monomethyl ether of polyethylene glycol to get waterborne materials with specific optical anisotropy. The extraction, modification, and morphology of the CNCs were investigated using NMR (Nuclear Magnetic Resonance), TEM (Transmission Electron Microscopy), XRD (X-ray Powder Diffraction), and FESEM (Field Emission Scanning Electron Microscopy) analysis. The prepared HPNC was analyzed using a hot stage POM (Polarized Optical Microscope) for optical anisotropy. The thermal stability of prepared CNCs and HPNC was also investigated. Upon optimization using rheology and POM, it was found that at the ratio of 1:1, HPNC (5 wt%) and mPEG (40 wt%) had the most distinct optical properties. The potential of the prepared materials can be further explored in sensing, smart coating, and security materials. (C) 2022 Elsevier B.V. All rights reserved.

10abagasse10aCellulose nanocrystals10aElliptical birefringence10aliquid crystals10aoptical anisotropy1 aSingh, Shiva1 aBhardwaj, Shakshi1 aVerma, Chhavi1 aChhajed, Monika1 aBalayan, Kajal1 aGhosh, Kaushik1 aMaji, Pradip, K. uhttp://library.ncl.res.in/content/elliptically-birefringent-chemically-tuned-liquid-crystalline-nanocellulose-composites01586nas a2200181 4500008004100000022001400041245010900055210006900164260000800233300001600241490000700257520093700264100001701201700001901218700001901237700001901256856012901275 2022 eng d a0020-166900aSix-membered saturated NHC-stabilized borenium cations: isolation of a cationic analogue of borinic acid0 aSixmembered saturated NHCstabilized borenium cations isolation o cAUG a12991-129970 v613 a

The reaction of six-membered saturated NHC [1,3-di(2,6-diisopropylphenyl) tetrahydropyrimidine-2-ylidene; henceforth abbreviated as 6-SIDipp] with PhBCl2 yields a Lewis base adduct, 6-SIDipp.PhBCl2 (1), which readily undergoes nucleophilic substitution reaction with AgNO3, leading to the single (2) and double (3) substitution of both chlorides with ONO2 moieties at the boron atom. The reaction of 1 with 1 equiv of AlCl3 resulted in a borenium cation of composition [6-SIDipp.B(Ph)Cl]+ (4) with AlCl4- as the counteranion. Although borenium cations with different substituents on boron have been reported, a structurally characterized phenylchloroborenium cation remains unknown. Similarly, the reaction of 1 with triflic acid provides the first representative of a new class of borenium cations bearing one hydroxyl and one phenyl group on boron (5), a cationic analogue of borinic acid. Ph-BN H Diphenylborinic acid

1 aKundu, Gargi1 aBalayan, Kajal1 aTothadi, Srinu1 aSen, Sakya, S. uhttp://library.ncl.res.in/content/six-membered-saturated-nhc-stabilized-borenium-cations-isolation-cationic-analogue-borinic01093nas a2200205 4500008004100000022001400041245010400055210006900159260000800228300001400236490000700250520037300257100001900630700002100649700001700670700002600687700002400713700001900737856013100756 2023 eng d a1359-734500aOn the competition between six-membered and five-membered NHC towards alane centered ring expansion0 acompetition between sixmembered and fivemembered NHC towards ala cJUL a8540-85430 v593 a

The combination of 6-SIDipp center dot AlH3 (1) and 5-IDipp resulted in the ring expansion of 6-NHC, while the five-membered NHC remained unchanged, which was subsequently explained by DFT studies. Besides, the substitution chemistry of 1 was also studied with TMSOTf and I-2, which gave rise to the substitution of a hydride by triflate or iodide ligands.

1 aBalayan, Kajal1 aSharma, Himanshu1 aVanka, Kumar1 aRavindranathan, Sapna1 aGonnade, Rajesh, G.1 aSen, Sakya, S. uhttp://library.ncl.res.in/content/competition-between-six-membered-and-five-membered-nhc-towards-alane-centered-ring-expansion02066nas a2200193 4500008004100000022001400041245014200055210006900197260000800266300001600274490000700290520135000297100001901647700002101666700001701687700002401704700001901728856012501747 2024 eng d a2041-652000aUncovering diverse reactivity of NHCs withdiazoalkane: C-H activation, C=C bond formation,and access to N-heterocyclic methylenehydrazine0 aUncovering diverse reactivity of NHCs withdiazoalkane CH activat cNOV a18387-183940 v153 a

N-heterocyclic carbenes (NHCs) have attracted significant attention due to their strong sigma-donating capabilities, as well as their transition-metal-like reactivity towards small molecules. However, their interaction with diazoalkanes remains understudied. In this manuscript, we explore the reactivity of a series of stable carbenes, encompassing a wide range of electronic properties, with Me3SiCHN2. 5-SIPr activates the C-H bond of Me3SiCHN2, resulting in the formation of a novel diazo derivative (1), while carbenes such as 5-IPr, 6-SIPr, and diamido carbene yield N-heterocyclic methylenehydrazine derivatives (3, 4, and 8). The reaction of Me3SiCHN2 with 5-ItBu unexpectedly leads to the formation of a triazole ring linked with the imidazole moiety via a CC double bond (6) alongside the azine product (7). Substituting the diazoalkane with diazoester consistently yields azine derivatives (9-12 and 14). Only in the case of 5-ItBu, an imidazolium salt with tetrazenide anion (13) was obtained as a side product. The reaction of 4 with HCl resulted in the desilylprotonation to form a salt, 5a, which undergoes deprotonation upon using bases such as Et3N and KHMDS to form N-heterocyclic methylene hydrazine, 5. Theoretical calculations have been conducted to elucidate the diverse mechanisms underlying product formation.

1 aBalayan, Kajal1 aSharma, Himanshu1 aVanka, Kumar1 aGonnade, Rajesh, G.1 aSen, Sakya, S. uhttp://library.ncl.res.in/content/uncovering-diverse-reactivity-nhcs-withdiazoalkane-c-h-activation-cc-bond-formationand