02001nas a2200157 4500008004100000022001400041245007500055210006900130260007100199300001400270490000800284520140900292100001501701700002101716856010601737 2014 eng d a1089-563900aIonization-induced tautomerization in cytosine and effect of solvation0 aIonizationinduced tautomerization in cytosine and effect of solv a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJUL a5323-53320 v1183 a

The recent observation of excitation-induced tautomerization in gas-phase cytosine motivated us to investigate the possibility of facile tautomerization in ionized cytosine and the effect of solvation on the tautomerization barriers. The tautomerization mechanisms were characterized at the density functional theory (DFT)omega B97X-D and coupled-cluster singles and doubles (CCSD) levels of theory. Vertical and adiabatic ionization energies (VIEs and AIEs, respectively) of the tautomers of cytosine and the microsolvated species were calculated with the equation-of-motion ionization-potential coupled-cluster (EOM-IP-CCSD) method. We observed that, in microsolvated cytosine, the solvatochromic shifts of the VIEs can be both blue- and red-shifted depending on the tautomers. This is explained by the analysis of the charge dipole interactions between the cytosine and water molecules. We noticed that, upon ionization, gas-phase tautomerization barriers are reduced by 0-4 kcal/mol, whereas microsolvated (with one water) tautomerization barriers are reduced by 4-5 kcal/mol. We also investigated the tautomerization process in solvation using a continuum model with one active water molecule in the quantum mechanical region. We noticed that, even though bulk solvation has a significant effect on ionization energies, its effect on the ionization-induced tautomerization barrier is minimal.

1 aDas, Tamal1 aGhosh, Debashree uhttps://library.ncl.res.in/content/ionization-induced-tautomerization-cytosine-and-effect-solvation-001648nas a2200181 4500008004100000022001400041245008600055210006900141260007100210300001600281490000800297520096300305100002001268700001501288700002601303700002101329856011601350 2015 eng d a1520-610600aFeasibility of ionization-mediated pathway for ultraviolet-induced melanin damage0 aFeasibility of ionizationmediated pathway for ultravioletinduced a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT a13288-132930 v1193 a

Melanin is the pigment found in human skin that is responsible for both photoprotection and photodamage. Recently there have been reports that greater photodamage of DNA occurs when cells containing melanin are irradiated with ultraviolet (UV) radiation, thus suggesting that the photoproducts of melanin cause DNA damage. Photoionization processes have also been implicated in the photodegradation of melanin. However, not much is known about the oxidation potential of melanin and its monomers. In this work we calculate the ionization energies of monomers, dimers, and few oligomers of eumelanin to estimate the threshold energy required for the ionization of eumelanin. We find that this threshold is within the UV-B region for eumelanin. We also look at the charge and spin distributions of the various ionized states of the monomers that are formed to understand which of the ionization channels might favor monomerization from a covalent dimer.

1 aMandal, Mukunda1 aDas, Tamal1 aGrewal, Baljinder, K.1 aGhosh, Debashree uhttps://library.ncl.res.in/content/feasibility-ionization-mediated-pathway-ultraviolet-induced-melanin-damage-001621nas a2200181 4500008004100000022001400041245018100055210006900236260011000305300001600415490000600431520079500437100002401232700002501256700001501281700001701296856012601313 2016 eng d a2046-206900aExploration of the diastereoselectivity in an unusual Grignard reaction and its application towards the synthesis of styryl lactones 7-epi-(+)-goniodiol and 8-epi-(-)-goniodiol0 aExploration of the diastereoselectivity in an unusual Grignard r aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcMAY a50721-507250 v63 a

An unusual diastereoselective Grignard reaction is explored, where the Grignard reagents are derived from 1,n-dihaloalkanes. A steric bias due to the presence of a quaternary centre adjacent to the acetonide ester at the benzylic position is responsible for the formation of an intramolecularly reduced product in almost quantitative yield. This steric hindrance is responsible for the diastereoselectivity observed with a variety of aromatic as well as aliphatic esters. The unusual Grignard reaction furnishes long chain secondary alcohols possessing a terminal olefin, which are synthetically important intermediates. As an application of this method, the diastereoselective synthesis of styryl lactones viz. 7-epi-(+)-goniodiol (29) and 8-epi(-)-goniodiol (30) has been achieved.

1 aChavan, Subhash, P.1 aKhatod, Harshali, S.1 aDas, Tamal1 aVanka, Kumar uhttps://library.ncl.res.in/content/exploration-diastereoselectivity-unusual-grignard-reaction-and-its-application-towards01375nas a2200205 4500008004100000022001400041245006500055210006300120260011000183300001400293490000700307520065500314100002600969700001900995700001401014700001501028700001701043700001901060856009001079 2016 eng d a1359-734500aFacile access to a Ge(II) dication stabilized by isocyanides0 aFacile access to a GeII dication stabilized by isocyanides aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcMAY a7890-78920 v523 a

Herein, we introduce isocyanide as a ligand in main group chemistry and describe the facile isolation of a Ge(II) dication. The reaction of 2,6-dimethylphenylisocyanide with GeCl2 leads to the formation of a Ge(II) dication with two [GeCl3](-) molecules as counter anions. The dicationic Ge(II) center is bound to four isocyanide ligands and also holds a lone pair of electrons. DFT calculations reveal that the dication is stabilized only by sigma-donation from the four isocyanide ligands. Natural population analysis gives a charge of +0.74 on the Ge(II) center, indicating that the positive charge is shared by the isocyanide substituents.

1 aSwamy, V., S. V. S. N1 aYadav, Sandeep1 aPal, Shiv1 aDas, Tamal1 aVanka, Kumar1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/facile-access-geii-dication-stabilized-isocyanides01367nas a2200193 4500008004100000022001400041245011300055210006900168260007100237300001400308490000700322520062500329100001700954700002400971700001500995700001701010700002001027856012601047 2016 eng d a0022-326300aIntramolecular dehydrogenative coupling of 2,3-diaryl acrylic compounds: access to substituted phenanthrenes0 aIntramolecular dehydrogenative coupling of 23diaryl acrylic comp a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJUL a5663-56690 v813 a

A simple, facile, and environmentally benign intramolecular dehydrogenative coupling of various 1,2-diarylethylenes for the synthesis of phenanthrenes in excellent yield has been described. This new methodology uses ceric ammonium nitrate (CAN) as a promoter at room temperature and has been extended to intermolecular synthesis of biaryl compounds. The electron transfer from methoxyarene to cerium leads to cationic radical formation, which further proceeds to intramolecular coupling. Preliminary mechanistic investigation by EPR spectroscopy and density functional theory calculation suggested a similar view.

1 aGupta, Vijay1 aRao, V., U. Bhaskar1 aDas, Tamal1 aVanka, Kumar1 aSingh, Ravi, P. uhttps://library.ncl.res.in/content/intramolecular-dehydrogenative-coupling-23-diaryl-acrylic-compounds-access-substituted01169nas a2200169 4500008004100000245007500041210006900116260000800185300001400193490000700207520060300214100002400817700001900841700001500860700001700875856010700892 2017 eng d00aDBU-mediated diastereoselective aldol-type cyanomethylation of isatins0 aDBUmediated diastereoselective aldoltype cyanomethylation of isa cAPR a4489-44960 v823 aAn efficient, metal-free approach to 3-substituted 3-hydroxybxindole by DBU-mediated highly diastereoselective addition of aryl acetonitrile to N-protected isatin under mild conditions has been developed. The reaction proceeds smoothly to produce respective cyanomethylated adducts in good yield and excellent diastereoselectivity. Further transformation of the cyanide group allowed the synthesis of an advance intermediate of corresponding (+/-) CPC analogue. The mechanistic insight :toward the aldol-type cyanomethylation, of N-tritylisatin with benzyl cyanide was obtained by DFT calculations.1 aRao, V., U. Bhaskar1 aKumar, Krishna1 aDas, Tamal1 aVanka, Kumar uhttps://library.ncl.res.in/content/dbu-mediated-diastereoselective-aldol-type-cyanomethylation-isatins00946nas a2200157 4500008004100000245010600041210006900147260000800216490000700224520034600231100002600577700002400603700001500627700001900642856012700661 2017 eng d00aMetal free mild and selective aldehyde cyanosilylation by a neutral penta-coordinate silicon compound0 aMetal free mild and selective aldehyde cyanosilylation by a neut cJUN0 v533 aThis study demonstrates the preparation and structural characterization of a Si(IV) hydride (PhC(NtBu)(2)SiH(CH3)Cl) (1) and its use as a catalyst for the cyanosilylation of a variety of aldehydes. Compound 1 represents the first neutral penta-coordinate silicon(IV) species that catalyzes cyanosilylation of aldehydes under mild conditions.1 aSwamy, V., S. V. S. N1 aBisai, Milan, Kumar1 aDas, Tamal1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/metal-free-mild-and-selective-aldehyde-cyanosilylation-neutral-penta-coordinate-silicon01151nas a2200169 4500008004100000245009700041210006900138260000800207300001600215490000700231520054600238100001700784700002000801700001500821700001900836856012600855 2017 eng d00aTransition metal free catalytic hydroboration of aldehydes and aldimines by amidinato silane0 aTransition metal free catalytic hydroboration of aldehydes and a cFEB a2420 - 24240 v463 aThe transition metal free catalytic hydroboration of aldehydes and ketones is very limited and has not been reported with a well-defined silicon(iv) compound. Therefore, we chose to evaluate the previously reported silicon(iv) hydride [PhC(NtBu)2SiHCl2], (1) as a single component catalyst and found that it catalyzes the reductive hydroboration of a range of aldehydes with pinacolborane (HBpin) under ambient conditions. In addition, compound 1 can catalyze imine hydroboration. DFT calculation was carried out to understand the mechanism.1 aBisai, Milan1 aPahar, Sanjukta1 aDas, Tamal1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/transition-metal-free-catalytic-hydroboration-aldehydes-and-aldimines-amidinato-silane00817nas a2200157 4500008004100000245012400041210006900165260000800234490000700242520022400249100001700473700001500490700001700505700001900522856011800541 2018 eng d00aEasily accessible lithium compound catalyzed mild and facile hydroboration and cyanosilylation of aldehydes and ketones0 aEasily accessible lithium compound catalyzed mild and facile hyd cAPR0 v543 aSimple and readily accessible lithium compounds such as 2,6-ditertbutyl phenolate lithium (1a), 1,1' dilithioferrocene (1b) and nacnac lithium (1c) are found to be efficient single site catalysts for hydroboration of...1 aBisai, Milan1 aDas, Tamal1 aVanka, Kumar1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/easily-accessible-lithium-compound-catalyzed-mild-and-facile-hydroboration-and01557nas a2200217 4500008004100000022001400041245009800055210006900153260000800222300001400230490000700244520081000251100002501061700003201086700001801118700001501136700001701151700002001168700002401188856012701212 2018 eng d a1359-734500aMechano-responsive room temperature luminescence variations of boron conjugated pyrene in air0 aMechanoresponsive room temperature luminescence variations of bo cJUN a6028-60310 v543 a

Stimuli responsive tunable luminescence is a promising field of research. Even though mechanofluorescence is widely studied, mechanophosphorescence remains unexplored. Here we report the mechano-driven fluorescence and phosphorescence variations of a pyrene tetraboronic ester derivative. The fluorochromic and room temperature phosphorescence features are supported by theoretical studies and single crystal analysis. The mechanically ground fluorescence active but phosphorescence inactive pyrene tetraboronic ester exhibits room temperature phosphorescence in air withmechanical force. The efficient intermolecular electronic coupling in the dimer formed upon scratching enables a good communication between singlet and triplet states, hence resulting in room temperature mechanophosphorescence.

1 aWakchaure, Vivek, C.1 aRanjeesh, Kayaramkodath, C.1 aGoudappagouda1 aDas, Tamal1 aVanka, Kumar1 aGonnade, Rajesh1 aBabu, Sukumaran, S. uhttps://library.ncl.res.in/content/mechano-responsive-room-temperature-luminescence-variations-boron-conjugated-pyrene-air01965nas a2200193 4500008004100000022001500041245010400056210006900160260000800229300001400237490000700251520128700258100001801545700002401563700001501587700001701602700002801619856012401647 2018 eng d a 2192-650600a Twelve-armed hexaphenylbenzene-based giant supramolecular framework for entrapping guest molecules0 aTwelvearmed hexaphenylbenzenebased giant supramolecular framewor cNOV a1032-10370 v833 a

Host-guest chemistry is a functional model in supramolecular chemistry for understanding specific process occurring in biological systems. Herein, we describe a rationally designed giant multiarmed hexaphenylbenzene (HPB)-based supramolecular frameworks which encapsulate a variety of guest molecules in the voids of their crystal lattice through the cooperative interplay of multivalency, noncovalent forces and backbone rigidity. In this connection, pseudo-axially substituted twelve-armed hexaphenylbenzene was synthesized and its molecular entrapping nature was studied by varying number of H-bond donor-acceptor sites in the arms. The per-methyl esterified HPB acted as a cavitand to include nonpolar and polar aprotic guests in its crystal structure via C-H center dot center dot center dot pi, C-H center dot center dot center dot O and C-H center dot center dot center dot N interactions. The corresponding amidated HPB showed unprecedented inclusion of ammonia and segregation of the guest molecules according to their polarity in the lattice. Furthermore, this molecular entrapping system has been used to obtain the crystal structure of a hitherto unproven 2-azaallenium intermediate, which had been proposed to be involved in aminomethylation of activated arenes.

1 aMadhu, Suresh1 aGonnade, Rajesh, G.1 aDas, Tamal1 aVanka, Kumar1 aSanjayan, Gangadhar, J. uhttps://library.ncl.res.in/content/twelve-armed-hexaphenylbenzene-based-giant-supramolecular-framework-entrapping-guest01605nas a2200205 4500008004100000022001400041245008900055210006900144260000800213520090400221653001001125653001801135653002401153653001101177653001201188100003301200700001501233700003001248856012101278 2019 eng d a2192-650600aBoron-conjugated pyrenes as fluorescence-based molecular probes and security markers0 aBoronconjugated pyrenes as fluorescencebased molecular probes an cJUL3 a

Boron-embedded aromatic hydrocarbons are a class of molecules known for their distinct electronic and/or optoelectronic properties and are thus suitable for many potential applications. Among those, boronic ester and acid containing molecules have been widely used for sensing and molecular recognition applications, respectively. We compared the sensing and molecular recognition properties of two boron-containing pyrene derivatives for fluoride and glucose sensing applications. The presence of four boronate ester groups enabled fluoride ion sensing at the mu M level. The boronic acid derivative is very selective towards glucose compared to other saccharides. Furthermore, we used the mechano-responsive fluorescence changes and self-assembly of these derivatives, respectively, for fluorescence-based inkless and ink (water)-based writing in invisible security labeling applications.

10aboron10acarbohydrates10amechanoluminescence10apyrene10asensors1 aWakchaure, Vivek, Chandrakan1 aDas, Tamal1 aBabu, Sukumaran, Santhosh uhttps://library.ncl.res.in/content/boron-conjugated-pyrenes-fluorescence-based-molecular-probes-and-security-markers01786nas a2200157 4500008004100000245006900041210006700110260000800177300001400185490000600199520128500205100001501490700002101505700001701526856008501543 2019 eng d00aInsights into the origin of life: did it begin from HCN and H2O?0 aInsights into the origin of life did it begin from HCN and H2O cSEP a1532-15400 v53 a

The seminal Urey-Miller experiments showed that molecules crucial to life such as HCN could have formed in the reducing atmosphere of the Hadean Earth and then dissolved in the oceans. Subsequent proponents of the "RNA World" hypothesis have shown aqueous HCN to be the starting point for the formation of the precursors of RNA and proteins. However, the conditions of early Earth suggest that aqueous HCN would have had to react under a significant number of constraints. Therefore, given the limiting conditions, could RNA and protein precursors still have formed from aqueous HCN? If so, what mechanistic routes would have been followed? The current computational study, with the aid of the ab initio nanoreactor (AINR), a powerful new tool in computational chemistry, addresses these crucial questions. Gratifyingly, not only do the results from the AINR approach show that aqueous HCN could indeed have been the source of RNA and protein precursors, but they also indicate that just the interaction of HCN with water would have sufficed to begin a series of reactions leading to the precursors. The current work therefore provides important missing links in the story of prebiotic chemistry and charts the road from aqueous HCN to the precursors of RNA and proteins.

1 aDas, Tamal1 aGhule, Siddharth1 aVanka, Kumar uhttps://library.ncl.res.in/content/insights-origin-life-did-it-begin-hcn-and-h2o01143nas a2200193 4500008004100000022001400041245008800055210006900143260000900212300001600221490000700237520049800244100002400742700001900766700001500785700001700800700001900817856011300836 2019 eng d a1359-734500aLithium compounds as single site catalysts for hydroboration of alkenes and alkynes0 aLithium compounds as single site catalysts for hydroboration of  cOCT  a11711-117140 v553 a

The hydroboration of alkenes and alkynes using easily accessible lithium compounds [2,6-di-tert-butyl phenolatelithium (1a) and 1,1 ` dilithioferrocene (1b)] has been achieved with good yields, high functional group tolerance and excellent chemoselectivity. Deuterium-labeling experiments confirm the cis-addition of pinacolborane. The methodology has been further extended to myrcene, which undergoes selective 4,3-hydroboration. DFT calculations provide insights into the mechanism.

1 aBisai, Milan, Kumar1 aYadav, Sandeep1 aDas, Tamal1 aVanka, Kumar1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/lithium-compounds-single-site-catalysts-hydroboration-alkenes-and-alkynes02105nas a2200157 4500008004100000245010900041210006900150260000800219520149800227100001901725700001701744700001501761700002401776700001801800856012901818 2019 eng d00a Phosphite-Catalyzed C-H allylation of azaarenes via an enantioselective [2,3]-Aza-wittig rearrangement 0 aPhosphiteCatalyzed CH allylation of azaarenes via an enantiosele cAUG3 a

A phosphite-mediated [2,3]-aza-Wittig rearrangement has been developed for the regio- and enantioselective allylic alkylation of six-membered heteroaromatic compounds (azaarenes). The nucleophilic phosphite adducts of N-allyl salts undergo a stereoselective base-mediated aza-Wittig rearrangement and dissociation of the chiral phosphite for overall C-H functionalization of azaarenes. This method provides efficient access to tertiary and quaternary chiral centers in isoquinoline, quinoline, and pyridine systems, tolerating a broad variety of substituents on both the allyl part and azaarenes. Catalysis with chiral phosphites is also demonstrated with synthetically useful yields and enantioselectivities.

1 aMotaleb, Abdul1 aRani, Soniya1 aDas, Tamal1 aGonnade, Rajesh, G.1 aMaity, Pradip uhttps://library.ncl.res.in/content/phosphite-catalyzed-c-h-allylation-azaarenes-enantioselective-23-aza-wittig-rearrangement02090nas a2200193 4500008004100000245005500041210005300096260000800149300001600157490000700173520150800180100002401688700002601712700001501738700001701753700002401770700001901794856008301813 2019 eng d00a Synthesis and reactivity of a hypersilylsilylene 0 aSynthesis and reactivity of a hypersilylsilylene cAUG a10536-105420 v583 a

Stabilization of an amidinatosilylene with a bulky tris(trimethylsilyl)silyl substituent was realized with the preparation of PhC(NtBu)(2)Si{Si(SiMe3)(3)} (1) from PhC(NtBu)(2)SiHCl2 with K{Si(SiMe3)(3)} in more than 90% yield. The highly deshielded Si-29 NMR resonance (delta = 76.91 ppm) can be attributed to the absence of a pi-donating substituent. The molecular structure of 1 shows a trigonal-planar geometry around the Si-II center with a Si-II-Si-IV bond length of 2.4339(13) angstrom. A series of reactions of 1 with Me3NO, S, Se, and Te were performed. While siloxane derivatives (2 and 3) are obtained from reactions with Me3NO, silachalcogenones (4-6) are formed with other chalcogens. The presence of Si=E (E = S, Se, and Te) bonds in 4-6 have been confirmed by single crystal X-ray studies. Silaoxirane (7) formation was observed when 1 was treated with acetone, demonstrating the importance of the tris(trimethylsilyl)silyl group to kinetically and thermodynamically protect the silaoxirane derivative with less bulky substituents on the C atom.

1 aBisai, Milan, Kumar1 aSwamy, V., S. V. S. N1 aDas, Tamal1 aVanka, Kumar1 aGonnade, Rajesh, G.1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/synthesis-and-reactivity-hypersilylsilylene01159nas a2200205 4500008004100000022001400041245009400055210006900149260000800218300001600226490000700242520046600249100002000715700002600735700001500761700002400776700001700800700001900817856011700836 2020 eng d a1359-734500aAccess to diverse germylenes and a six-membered dialane with a flexible beta-diketiminate0 aAccess to diverse germylenes and a sixmembered dialane with a fl cOCT a11871-118740 v563 a

A nacnac-based tridentate ligand containing a picolyl group (L) was employed to isolate chlorogermylene (1). The reaction of1with another equivalent of GeCl2 center dot dioxane surprisingly gave pyridylpyrrolide-based chlorogermylene (2)viaC-N bond cleavage and C-C coupling, while with AlCl3, it afforded a transmetalated product,4. The reaction of L with AlH3 center dot NMe2Et led to an unusual cyclohexane type six-membered dialane heterocycle (5).

1 aPahar, Sanjukta1 aSwamy, V., S. V. S. N1 aDas, Tamal1 aGonnade, Rajesh, G.1 aVanka, Kumar1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/access-diverse-germylenes-and-six-membered-dialane-flexible-beta-diketiminate01732nas a2200181 4500008004100000022001400041245009600055210006900151260000900220300001600229490000600245520108200251100002501333700002401358700001501382700003001397856012301427 2020 eng d a2050-748800aDual mode selective detection and differentiation of TNT from other nitroaromatic compounds0 aDual mode selective detection and differentiation of TNT from ot cJUN  a10767-107710 v83 a

Selective detection of explosives, especially TNT, is a highly desirable area of research and various explosives detection devices including fluorescent sensors are already in place. However, multi-mode sensors will be more useful and reliable than conventional fluorescent ``Turn Off'' sensors. One of the challenges is the development of selective sensors to prevent illegal transport of commonly used explosive TNT through on-the-spot analysis. In this context, we report a fluorescent polymer-based selective detection of TNT using both fluorometric and colorimetric signals. In addition, colorimetric differentiation of TNT from other nitroaromatic compounds is made possible by complexing with various amines. Even though many other sensors are available for TNT, the current demonstration is unique in terms of selectivity, sensitivity, reliability, portability, and rapidity of results. The as-developed explosive detection kit can be useful in both civilian and military operations to trace the illegal transport of TNT as well as for post-explosion analysis.

1 aPatil, Goudappagouda1 aDongre, Sangram, D.1 aDas, Tamal1 aBabu, Sukumaran, Santhosh uhttps://library.ncl.res.in/content/dual-mode-selective-detection-and-differentiation-tnt-other-nitroaromatic-compounds02071nas a2200289 4500008004100000022001400041245015700055210006900212260000900281300001100290490000800301520110100309653002101410653001501431653001201446653001601458653001301474653002101487100002401508700002301532700001501555700002101570700001901591700001701610700002301627856013101650 2020 eng d a0022-328X00aTransmetallation vs adduct: diverse reactivity of N,O-ketiminato germylene with [Cp*MCl2](2) (M = Rh or Ir; Cp* = eta(5)-C5Me5) and MCl5 (M = Nb and Ta)0 aTransmetallation vs adduct diverse reactivity of NOketiminato ge cAPR  a1211420 v9113 a

The reactions of the germylenes, [(Dipp)NCMeCHCORGeCl] (1a: R = Me, 1b: R = Ph) with [Ir2Cl2(mu-Cl)(2)(eta(5)-Cp*)(2)] led to the formation of the adducts [(Dipp)NCMeCHCORGeClIrCl2Cp*] (3a: R = Me and 3b: R = Ph). On the other hand, [Rh2Cl2(mu-Cl)(2)(eta(5)-Cp*)(2)] does not react with the germylenes (1a and 1b). When the reactions of 1a and 1b are carried out with [Cp*TaCl4], the reaction led to decomposition. The reaction of 1a or 1b with TaCl5 yielded the transmetallated products [(Dipp)NCMeCHCORTaCl4] (4a: R = Me, 4b: R = Ph) with the extrusion of GeCl2. Our theoretical studies show that for, the insertion of TaCl5 to 1a and the formation of 4a with concomitant elimination of GeCl2 is energetically favourable. Extrusion of SnCl2 is also observed when the corresponding stannylene, [(Dipp)NCMeCHCOMeSnCl] was reacted with TaCl5. All these compounds have been characterized by H-1 and C-13 NMR spectroscopy, elemental analysis and the constitution of compounds 1b, 3b, and 4a were confirmed by single-crystal X-ray crystallography. (C) 2020 Elsevier B.V. All rights reserved.

10aAdduct formation10aGermylenes10aIridium10aKetoiminate10aTantalum10aTransmetallation1 aRaghavendra, Beesam1 aBakthavachalam, K.1 aDas, Tamal1 aRoisnel, Thierry1 aSen, Sakya, S.1 aVanka, Kumar1 aGhosh, Sundargopal uhttps://library.ncl.res.in/content/transmetallation-vs-adduct-diverse-reactivity-no-ketiminato-germylene-cpmcl22-m-rh-or-ir-cp01122nas a2200217 4500008004100000022001400041245007300055210006900128260000900197300001400206490000700220520043800227100001700665700002300682700002400705700001900729700001500748700001700763700001900780856010500799 2021 eng d a1359-734500aDiverse reactivity of carbenes and silylenes towards fluoropyridines0 aDiverse reactivity of carbenes and silylenes towards fluoropyrid cMAY  a4428-44310 v573 a

The reaction of IDipp with C5F5N led to functionalization of all three carbon atoms of the imidazole ring with HF2- as the counter-anion (1). Reactivity with 2,3,5,6-tetrafluoropyridine gives only C-F bond activation leaving C-H bonds intact (5b). The reaction of SIDipp with C5F5N in the presence of BF3 afforded the ring cleavage product (3). Analogous reactions with silylene led to oxidative addition at the Si(II) center.

1 aKundu, Gargi1 aAjithkumar, V., S.1 aBisai, Milan, Kumar1 aTothadi, Srinu1 aDas, Tamal1 aVanka, Kumar1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/diverse-reactivity-carbenes-and-silylenes-towards-fluoropyridines01938nas a2200193 4500008004100000022001400041245012200055210006900177260000800246300001600254490000700270520121800277100003301495700001801528700001501546700002601561700003001587856012701617 2021 eng d a2040-336400aExcimer to exciplex transition through realization of donor-acceptor interactions in luminescent solvent-free liquids0 aExcimer to exciplex transition through realization of donoraccep cJUN a10780-107840 v133 aLuminescent solvent-free organic liquids are known for their enhanced quantum yield, color tunability, and availability of a matrix for other dopants to generate hybrid luminescent materials with improved features for newer applications. Herein, we report a donor-acceptor based luminescent ``exciplex liquid'' by utilizing the slightly different electron affinity of the acceptor molecules. A red-shifted broad exciplex emission exhibited by the donor-acceptor pair even at a lower concentration of the acceptor (0.001 equiv.) indicates high efficiency in the solvent-free state. A detailed NMR study revealed weak intermolecular interactions between the donor and acceptor in the solvent-free matrix that stabilizes the exciplex liquid. The failure of structurally similar solid counterparts to form an exciplex confirms the advantage of the available supportive liquid matrix. Besides, the luminescent exciplex liquid is found efficient in sensing application, which is unachievable by either the individual liquids or their solid counterparts. Here, a transition of a donor-acceptor pair from a solid to solvent-free liquid results in a new hybrid liquid that can be an alternative for solid sensor materials.1 aWakchaure, Vivek, Chandrakan1 aGoudappagouda1 aDas, Tamal1 aRavindranathan, Sapna1 aBabu, Sukumaran, Santhosh uhttps://library.ncl.res.in/content/excimer-exciplex-transition-through-realization-donor-acceptor-interactions-luminescent01612nas a2200229 4500008004100000022001400041245009200055210006900147260000900216300001100225490000600236520083200242653003301074653002601107653003001133653004001163653002801203100002501231700001501256700001701271856009401288 2021 eng d a2296-264600aInsights into chemical reactions at the beginning of the universe: from HeH+ to H-3 (+)0 aInsights into chemical reactions at the beginning of the univers cJUN  a6797500 v93 aAt the dawn of the Universe, the ions of the light elements produced in the Big Bang nucleosynthesis recombined with each other. In our present study, we have tried to mimic the conditions in the early Universe to show how the recombination process would have led to the formation of the first ever formed diatomic species of the Universe: HeH+, as well as the subsequent processes that would have led to the formation of the simplest triatomic species: H-3 (+). We have also studied some special cases: higher positive charge with fewer number of hydrogen atoms in a dense atmosphere, and the formation of unusual and interesting linear, dicationic He chains beginning from light elements He and H in a positively charged atmosphere. For all the simulations, the ab initio nanoreactor (AINR) dynamics method has been employed.10aab initio molecular dynamics10aab initio nanoreactor10aDensity functional theory10aorigin of molecules in the universe10athe earliest lewis acid1 aDash, Soumya, Ranjan1 aDas, Tamal1 aVanka, Kumar uhttps://library.ncl.res.in/content/insights-chemical-reactions-beginning-universe-heh-h-301019nas a2200193 4500008004100000022001400041245010100055210006900156260000800225300001400233490000700247520034600254100002400600700001800624700001500642700001700657700001900674856013200693 2021 eng d a1477-922600aLithium compound catalyzed deoxygenative hydroboration of primary, secondary and tertiary amides0 aLithium compound catalyzed deoxygenative hydroboration of primar cFEB a2354-23580 v503 a

A selective and efficient route for the deoxygenative reduction of primary to tertiary amides to corresponding amines has been achieved with pinacolborane (HBpin) using simple and readily accessible 2,6-di-tert-butyl phenolate lithium center dot THF (1a) as a catalyst. Both experimental and DFT studies provide mechanistic insight.

1 aBisai, Milan, Kumar1 aGour, Kritika1 aDas, Tamal1 aVanka, Kumar1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/lithium-compound-catalyzed-deoxygenative-hydroboration-primary-secondary-and-tertiary-amides01608nas a2200193 4500008004100000022001400041245010300055210006900158260001100227300001100238490000800249520094000257100002401197700001801221700001501239700001701254700001901271856012401290 2021 eng d a0022-328X00aReadily available lithium compounds as catalysts for the hydroboration of carbodiimides and esters0 aReadily available lithium compounds as catalysts for the hydrobo cSEP 15 a1219240 v9493 aSelective and efficient hydroboration of esters and carbodiimides to alcohols and amines by two welldefined and readily accessible lithium complexes, 2,6-di-tert-butyl phenolate lithium (1a ) and 1,1'-dilithioferrocene (1b ) are described. A range of aliphatic, aromatic, and cyclic esters with various functional groups were selectively converted into the corresponding boronate esters. Similarly, the single hydroboration of carbodiimides with aliphatic and aromatic substituents on the nitrogen atoms was studied. A possible mechanistic pathway of the hydroboration of carbodiimides with HBpin has been proposed using NMR studies and DFT calculations. These reactions are convenient alternatives to stoichiometric hydride reduction or hydrogenation. The employing of lithium complexes is also significant, because of the need to find cheap and green alternatives to noble metal complexes. (C) 2021 Elsevier B.V. All rights reserved.1 aBisai, Milan, Kumar1 aGour, Kritika1 aDas, Tamal1 aVanka, Kumar1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/readily-available-lithium-compounds-catalysts-hydroboration-carbodiimides-and-esters01311nas a2200241 4500008004100000022001400041245004000055210003500095260000900130300001600139490000700155520067300162653002000835653000800855653001300863653002300876100002400899700001500923700001700938700002400955700001900979856007100998 2021 eng d a1433-785100aUnsymmetrical sp(2)-sp(3) disilenes0 aUnsymmetrical sp2sp3 disilenes cSEP  a20706-207100 v603 aDisilenes with differently coordinated silicon atoms are not known. Here, we have shown the high yield synthesis of a range of disilenes (2-4 and 6) upon reaction of a hypersilyl silylene PhC(NtBu)(2)SiSi(SiMe3)(3) (1) with aliphatic chlorophosphines. The most striking characteristic of these disilenes is the presence of two differently coordinated Si atoms (one is three-coordinated, the other four-coordinated). The analogous reaction with Ph2PCl did not afford the desired disilene, but, surprisingly, led to the first tetraphosphinosilane (8). DFT calculations were performed to understand the bonding in disilenes and differences in reactivity of the complexes.10achlorophosphine10aDFT10adisilene10ahypersilylsilylene1 aBisai, Milan, Kumar1 aDas, Tamal1 aVanka, Kumar1 aGonnade, Rajesh, G.1 aSen, Sakya, S. uhttps://library.ncl.res.in/content/unsymmetrical-sp2-sp3-disilenes02086nas a2200265 4500008004100000022001400041245012300055210006900178260000800247300000700255490000700262520120300269653001501472653002201487653002101509653001801530653001901548100002201567700001501589700002301604700002101627700001901648700002601667856012701693 2024 eng d a0334-212300aNew record of larval-pupal endoparasitoid Exorista deligata parasitising Indian Tea looper Hyposidra talaca from India0 aNew record of larvalpupal endoparasitoid Exorista deligata paras cMAR a230 v523 a

This is the first record of Exorista deligata (Pandell & eacute;, 1896) (Diptera: Tachinidae) as a parasitoid of Hyposidra talaca (Walker, 1860) (Lepidoptera: Geometridae) from India. H. talaca is a major and new emerging defoliator of the Tea plant Camellia sinensis (L) Kuntze (Theaceae). It completes multiple generations per year without diapause on C. sinensis, resulting in heavy crop loss. The field-collected larvae/pupa of H. talaca were checked for parasitoid infestations and reared until either the host or parasitoid emerged. The parasitoid was identified as E. deligata with morphological characteristics and confirmed by the mitochondrial cytochrome oxidase subunit-I (COX-CO1) gene sequencing technique. The parasitoid is infrequent with unexplored parasitic biology. It parasitises the larva and completes its lifecycle inside the developing H. talaca by entirely devouring the host. The mean percent parasitisation caused by E. deligata studied herein was 25.4% (range 5.88%-57.69%). Based on its parasitisation ability, we suggest the species could be a potential biological control agent to address the damage mitigation caused by the tea looper pest, H. talaca.

10aBiocontrol10aExorista deligata10aHyposidra talaca10aInvasive pest10aParasitisation1 aSharma, Pooja, V.1 aDas, Tamal1 aMukherjee, Susmita1 aPathan, Ejaj, K.1 aRahman, Azizur1 aGathalkar, Ganesh, B. uhttps://library.ncl.res.in/content/new-record-larval-pupal-endoparasitoid-exorista-deligata-parasitising-indian-tea-looper01989nas a2200205 4500008004100000022001400041245017100055210006900226260000800295300001400303490000700317520119400324100002601518700002801544700002401572700001501596700001701611700002501628856013001653 2024 eng d a2044-475300aNickel-catalyzed tandem conversion of paraformaldehyde : methanol to hydrogen and formate/chemo- and stereoselective hydrogenation of alkynes under neutral conditions0 aNickelcatalyzed tandem conversion of paraformaldehyde methanol t cMAY a2779-27930 v143 a

The development of new catalytic protocols for clean and COx-free hydrogen generation from fundamental feedstocks is always interesting and challenging. Herein, we disclose nickel-catalyzed dihydrogen generation from a mixture of paraformaldehyde-methanol under base-free and activator-free conditions. The dihydrogen generation from this redox combination under neutral, oxidative coupling conditions has been integrated with the hydrogen transfer reactions such as chemo- and stereoselective hydrogenation of alkynes in a tandem manner. This unprecedented strategy provides diverse highly stereoselective olefins with excellent tolerance of reducible functional groups such as ether, silyl ether, aldehyde, keto, ester, nitrile, halides including bromo and iodo groups, and heteroarenes. Additionally, we demonstrated catalytic stereo-interconversion of alkenes under benign conditions. The affordable gram-scale synthesis of some important pharmaceutical bioactive molecules has further enhanced their synthetic value. A tandem dihydrogen generation from a mixture of paraformaldehyde-methanol under base-free conditions followed by semihydrogenation of alkynes is reported.

1 aSubaramanian, Murugan1 aPadhy, Subarna, Sukanya1 aGouda, Chandrakanth1 aDas, Tamal1 aVanka, Kumar1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/nickel-catalyzed-tandem-conversion-paraformaldehyde-methanol-hydrogen-and-formatechemo-and00891nas a2200265 4500008004100000022001400041245011500055210007000170260000900240300001600249490000700265653001500272653001700287653001500304653001500319100002500334700001700359700001900376700002100395700001500416700002000431700002000451700001700471856013700488 2024 eng d a1359-734500aUnravelling the prebiotic origins of the simplest α-ketoacids in cometary ices: a computational investigation0 aUnravelling the prebiotic origins of the simplest αketoacids in  cOCT  a11283-112860 v6010aGLYOXYLATE10aHydrocarbons10aMetabolism10aPrecursors1 aDash, Soumya, Ranjan1 aPandya, Rinu1 aSingh, Geetika1 aSharma, Himanshu1 aDas, Tamal1 aHaldar, Hritwik1 aHotha, Srinivas1 aVanka, Kumar uhttps://library.ncl.res.in/content/unravelling-prebiotic-origins-simplest-%CE%B1-ketoacids-cometary-ices-computational-investigation