@article { ISI:000230717500014, title = {Metalloantitubercular compounds part 3: synthesis, crystal structure, spectroscopy, electrochemistry and antimycobacterial activity of the copper(II) ciproploxacin (cfH) complex and its phenanthroline adduct}, journal = {Transition Metal Chemistry}, volume = {30}, number = {3}, year = {2005}, month = {APR}, pages = {334-340}, publisher = {SPRINGER}, type = {Article}, address = {VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS}, abstract = {

The X-ray crystal structures of two ciprofloxacin compounds, viz. [Cu(cfH)(2)(Cl)(2)] (.) 2MeOH (.) 6H2O (2) and [Cu(cfH)(phen)Cl]BF4 (.) 4H(2)O (3) are reported. Complex ( 2) has a distorted octahedral geometry, whereas for the nitrogen adduct (3) a distorted square-pyramidal geometry is seen. Significant enhancement in the antimycobacterial activity of the copper conjugates correlates with their copper redox couples (Cu2+/Cu+) probably due to its relevance to intracellular accumulations and subsequent role in generating oxidative stress.

}, issn = {0340-4285}, doi = {10.1007/s11243-004-5861-2}, author = {Saha, D. K. and Patitungkho, S. and Padhye, S. and Deobagkar, D. N. and Ozarkar, A. and Bhadbhade, Mohan M. and Gonnade, Rajesh G.} } @article { ISI:000261711400041, title = {Molecular association via halogen bonding and other weak interactions in the crystal structures of 11-bromo-12-oxo-5 beta-cholan derivatives}, journal = {Journal of Molecular Structure}, volume = {892}, number = {1-3}, year = {2008}, month = {DEC}, pages = {246-253}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Methyl 3 alpha,7 alpha-diacetoxy-12-oxo-5 beta-cholan-24-oate 2, methyl 11 alpha-bromo-3 alpha,7 alpha-diacetoxy-12-oxo-5 beta-cholan-24-oate 3, methyl 11 beta-bromo-3 alpha,7 alpha-diacetoxy-12-oxo-5 beta-cholan-24-oate 4 and methyl 11,11-dibromo-3 alpha,7 alpha-diacetoxy-12-oxo-5 beta-cholan-24-oate 5 were synthesized. The crystal structures of these molecules were resolved to study the effect of bulky bromine atom in the steroid skeleton of cholic acid with different stereo-chemical orientations at C-11 on the two-dimensional arrangement of molecules and solid-state properties. All the molecules associate only via weak intermolecular interactions in their crystal structures, notable one being the Halogen Bonded assembly (C-Br center dot center dot center dot O) in 5. (C) 2008 Elsevier B.V. All rights reserved.

}, keywords = {11-Bromosteroids, Cholic acid, crystal structure, Halogen bonding}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2008.05.051}, author = {Salunke, Deepak B. and Hazra, Braja G. and Gonnade, Rajesh G. and Pore, Vandana S. and Bhadbhade, Mohan M.} } @article { ISI:000272896300048, title = {Magnetic phase transition in valence tautomers as polymorphs of 3-iodolawsone: Single crystal X-ray structure, DSC and EPR studies}, journal = {Journal of Molecular Structure}, volume = {938}, number = {1-3}, year = {2009}, month = {DEC}, pages = {328-335}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Three polymorphs of 3-iodolawsone (I-III) have been isolated and characterized by single crystal X-ray diffraction, electron paramagnetic resonance (EPR) spectroscopy and differential scanning calorimetry (DSC) techniques. Polymorphs I and II were crystallized from methanol in two different valence tautomeric forms: hydroxynaphthoquinone (HNQ) and hydroxynaphthoseimquinone (HNSQ) as needles and thick plates, respectively. Polymorph III was crystallized from ethanol in HNQ form, as thin plates Chiral crystals of I belongs to the orthorhombic P2(1)2(1)2(1) space group: II and III belong to the monochnic non-centrosymmetric space group Cc. The molecules are packed via O-H O bonding and pi . pi stacking interactions. The study reveals that relatively stronger intermolecular H-bonding (2.02 angstrom) and most favoured pi . pi stacking (similar to 3 49 angstrom) interactions lead II to HNSQ radicals, presence of which was confirmed by EPR (g = 2.0052) spectroscopy. Interestingly, these materials exhibit crystal-to-crystal magnetic phase transition from polymorph I (diamagnetic) to polymorph II (paramagnetic structure) at 171.1 degrees C as identified by DSC and X-ray crystallographic studies (C) 2009 Elsevier B.V. All rights reserved

}, keywords = {3-Iodolawsone, Hydroxynaphthoquinone (HNQ), Hydroxynaphthosemiquinone radical (HNSQ), Magnetic phase transition, Polymorphs, Valence tautomers}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2009.10.005}, author = {Zaware, Santosh B. and Dagade-Waghmode, Shobha and Gonnade, Rajesh G. and Srinivas, Darbha and Rane, Sandhya Y.} } @article { ISI:000310068800011, title = {Multifaceted folding in a foldamer featuring highly cooperative folds}, journal = {Chemical Communications}, volume = {48}, number = {91}, year = {2012}, month = {SEP}, pages = {11205-11207}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Herein, we report on the folding pattern observed in a synthetic peptide featuring two highly mutually dependent, yet strikingly dissimilar, closed networks of hydrogen-bonded rings that work in a cumulative fashion to stabilize the entire folded architecture of the peptide. Structural studies unequivocally suggest that disruption of any one of these mutually-dependent hydrogen-bonded networks is deleterious to the stability of the fully folded conformation of the peptide.

}, issn = {1359-7345}, doi = {10.1039/c2cc35649j}, author = {Ramesh, Veera V. E. and Priya, Gowri and Kotmale, Amol S. and Gonnade, Rajesh G. and Rajamohanan, Pattuparambil R. and Sanjayan, Gangadhar J.} } @article { ISI:000328864800088, title = {Multicomponent reactions involving arynes, quinolines, and aldehydes}, journal = {Organic Letters}, volume = {15}, number = {17}, year = {2013}, month = {SEP}, pages = {4620-4623}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The multicomponent reaction involving arynes, quinolines, and aldehydes leading to the diastereoselective synthesis of benzoxazino quinoline derivatives in good yields proceeding via 1,4-zwitterionic intermediates is reported. In addition, the synthetic potential of various carbonyl compounds in this reaction as well as the utility of isoquinoline as the nucleophilic trigger has been examined.

}, issn = {1523-7060}, doi = {10.1021/ol4023134}, author = {Bhunia, Anup and Porwal, Digvijay and Gonnade, Rajesh G. and Biju, Akkattu T.} } @article { ISI:000341359000029, title = {Multicomponent reactions involving phosphines, arynes and aldehydes}, journal = {Chemical Communications}, volume = {50}, number = {77}, year = {2014}, month = {AUG}, pages = {11389-11392}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Although nucleophilic phosphine-catalysis is a powerful tool for the construction of various carbocycles and heterocycles, the reactions in which phosphines are incorporated into the final product are rare, and the reports on phosphine addition to highly electrophilic arynes are scarce. Herein, we report the phosphine triggered multicomponent reaction of arynes and aldehydes, which takes place via the formal [3+2] cycloaddition of an initially generated 1,3-phosphonium zwitterion from phosphines and arynes with aldehydes. The reaction resulted in the formation of a diverse range of stable pentacovalent phosphoranes in good yields based on the benzooxaphosphole system.

}, issn = {1359-7345}, doi = {10.1039/c4cc05420b}, author = {Bhunia, Anup and Kaicharla, Trinadh and Porwal, Digvijay and Gonnade, Rajesh G. and Biju, Akkattu T.} } @article { ISI:000362436800075, title = {Mono- and binuclear palladacycles via regioselective C-H bond activation: syntheses, mechanistic insights and catalytic activity in direct arylation of azoles}, journal = {RSC Advances}, volume = {5}, number = {99}, year = {2015}, month = {SEP}, pages = {81502-81514}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

{Regioselective C-H bond palladation of the hybrid pincer-type ligands, 3-R2PO-C6H4-1-(CH2NPr2)-Pr-i [(POCNiPr2)-P-R2-H; R = Ph (1a)

}, issn = {2046-2069}, doi = {10.1039/c5ra18289a}, author = {Pandey, Dilip K. and Khake, Shrikant M. and Gonnade, Rajesh G. and Punji, Benudhar} } @article {42739, title = {Mechanistic insights into pincer-ligated palladium-catalyzed arylation of azoles with aryl Iodides: evidence of a Pd-II-Pd-IV-Pd-II pathway}, journal = {Organometallics}, volume = {35}, year = {2016}, month = {MAR}, pages = {875{\textendash}886}, abstract = {

Pincer-based (R2POCNR'2)PdCl complexes along with CuI cocatalyst catalyze the arylation of azoles with aryl iodides to give the 2-arylated azole products. Herein, we report an extensive mechanistic investigation for the direct arylation of azoles involving a well-defined and highly efficient (iPr2POCNEt2)PdCl (2a) catalyst, which emphasizes a rare PdII{\textendash}PdIV{\textendash}PdII redox catalytic pathway. Kinetic studies and deuterium labeling experiments indicate that the C{\textendash}H bond cleavage on azoles occurs via two distinct routes in a reversible manner. Controlled reactivity of the catalyst 2a underlines the iodo derivative (iPr2POCNEt2)PdI (3a) to be the resting state of the catalyst. The intermediate species (iPr2POCNEt2)Pd-benzothiazolyl (4a) has been isolated and structurally characterized. A determination of reaction rates of compound 4a with electronically different aryl iodides has revealed the kinetic significance of the oxidative addition of the C(sp2){\textendash}X electrophile, aryl iodide, to complex 4a. Furthermore, the reactivity behavior of 4a suggests that the arylation of benzothiazole proceeds via an oxidative addition/reductive elimination pathway involving a (iPr2POCNEt2)PdIV(benzothiazolyl)(Ar)I species, which is strongly supported by DFT calculations.

}, doi = {10.1021/acs.organomet.6b00003}, author = {Khake, Shrikant M. and Jagtap, Rahul A. and Dangat, Yuvraj B. and Gonnade, Rajesh G. and Vanka, Kumar and Punji, Benudhar} } @article {44114, title = {Modular approach towards functionalized highly stable self-complementary quadruple hydrogen bonded systems}, journal = {Organic \& Biomolecular Chemistry}, volume = {15}, year = {2017}, month = {DEC}, pages = {10087-10094}, type = {Article}, abstract = {Self-complementary quadruple hydrogen bonded systems have shown potential as key building blocks for developing various supramolecular polymers. Opportunities for the introduction of multiple functionalities would further augment, in principle, their application potential. Herein, we report a novel modular approach to simultaneously introduce two closely aligned side chains into AADD-type self-complementary quadruple hydrogen-bonding systems. Dithiane-tethered ureidopyrimidinone has been used as a reactive intermediate to efficiently attach closely aligned side chains by simply reacting with amines to form highly stable molecular duplexes. These duplexes featuring AADD-type arrays of hydrogen bonding codes are highly stable in non-polar solvents (K-dim > 1.9 x 10(7) M-1 in CDCl3) as well as in polar solvents (K-dim > 10(5) in 10\% DMSO-d(6)/CDCl3). Another notable feature of these self-assembling systems is their insensitivity to prototropy-related issues owing to their prototropic degeneracy, which will enhance their application potential in supramolecular chemistry.}, doi = {10.1039/c7ob02358h}, author = {Rayavarapu, Suresh and Kheria, Sanjeev and Shinde, Dinesh R. and Gonnade, Rajesh G. and Sanjayan, Gangadhar J.} } @article {44620, title = {Mechanism of nickel(II)-catalyzed C(2)-H alkynylation of indoles with alkynyl bromide}, journal = {Organometallics}, volume = {37}, year = {2018}, month = {JUL}, pages = {2037-2045}, abstract = {

The nickel system (THF)(2)NiBr2/phen has recently been shown as an efficient catalyst for the C-H bond alkynylation of diverse heteroarenes with (triisopropylsilyl)alkynyl bromide via monodentate chelation assistance. Herein, we report an extensive mechanistic investigation for the direct alkynylation of indoles involving the well-defined nickel catalyst, which features a coordinative insertion pathway of alkynyl bromide with the Ni(II) catalyst. Catalytic relevant nickel complexes, (phen)NiCl2 (5), (phen)(2)NiCl2 (6) and [(phen)(3)Ni].NiCl4 (7) were isolated, and the complexes 6 and 7 were structurally characterized. Well-defined complexes were as competent as the in situ generated catalyst system (THF)(2)NiBr2/phen for the alkynylation of indoles. Various controlled studies and reactivity experiments were performed to understand the probable pathway for the alkynylation reaction. Kinetics analysis highlights that the complex (phen)NiX2 acts as a precatalyst, and the involvement of substrate indole and LiO{\textquoteright}Bu are essential for the generation of the active catalyst. Deuterium labeling and kinetic studies suggest that the process involving C-H cleavage and carbo-nickelation of indole is a crucial rate influencing step. Reactivity study of various alkynyl compounds with nickel-species highlights a migratory insertion route for the reaction. DFT calculations firmly support the experimental findings and suggest the coordinative insertion pathway of alkynyl bromide rather than oxidative addition toward the nickel(II) center.

}, issn = {0276-7333}, doi = {10.1021/acs.organomet.8b00177}, author = {Khake, Shrikant M. and Jain, Shailja and Patel, Ulhas N. and Gonnade, Rajesh G. and Vanka, Kumar and Punji, Benudhar} } @article {44517, title = {Mechanistic aspects of pincer nickel(II)-catalyzed C-H bond alkylation of azoles with alkyl halides}, journal = {Organometallics}, volume = {37}, year = {2018}, month = {MAR}, pages = {1017-1025}, abstract = {

The quinolinyl-based pincer nickel complex, kappa(N),kappa(N),kappa(N)-{C9H6N-(mu-N)-C6H4-NMe2}NiCl [((NNNMe2)-N-Q)-NiCl; (1)] has recently been demonstrated to be an efficient and robust catalyst for the alkylation of azoles with alkyl halides under copper-free conditions. Herein, we report the detailed mechanistic investigation for the alkylation of azoles catalyzed by ((NNNMe2)-N-Q)NiCl (1), which highlights an iodine atom transfer (IAT) mechanism for the reaction involving a Ni-II/Ni-III process. Deuterium labeling experiments indicate reversible cleavage of the benzothiazole C-H bond, and kinetic studies underline a fractional negative rate order with the substrate benzothiazole. The involvement of an alkyl radical during the alkylation is validated by radical clock and external additive experiments. An active intermediate species ((NNNMe2)-N-Q)Ni(benzothiazolyl) (5a) has been isolated and structurally characterized. The complex ((NNNMe2)-N-Q)Ni(benzothiazoly1) (5a) is found to be the resting state of catalyst 1. Kinetic analysis of electronically different intermediates suggests that the step involving the reaction of 5a with alkyl iodide is crucial and a rate-influencing step. DFT calculations strongly support the experimental findings and corroborate an IAT process for the alkylation reaction.

}, issn = {0276-7333}, doi = {10.1021/acs.organomet.8b00025}, author = {Patel, Ulhas N. and Jain, Shailja and Pandey, Dilip K. and Gonnade, Rajesh G. and Vanka, Kumar and Punji, Benudhar} } @article {47119, title = {Metal halide structure and the extent of distortion control the photo-physical properties of luminescent zero dimensional organic-antimony(iii) halide hybrids}, journal = {Journal of Materials Chemistry C}, volume = {9}, year = {2021}, month = {JAN }, pages = {348-358}, type = {Article}, abstract = {

Antimony(iii) halide based zero dimensional hybrids have gained attention as broadband emitters. Until now, quadrangular pyramidal SbX5 based and octahedral SbX6 based 0D hybrids have been reported utilizing different organic ligands demonstrating some structural tunability affecting their emissive properties. Utilizing a common organic ligand, here we demonstrate the structural tunability (quadrangular pyramidal, octahedral, or a combination thereof) of the metal halide unit in Sb(iii)Cl 0D hybrids with contrasting photo-physical properties (broadband, Stokes shift, strong/weak colored emission). The structure-property-mechanism correlation of the synthesized compounds [1 (C12H52Cl18N8O4Sb3; tris Sb green); 2 (C12H50Cl14N8O3Sb2; tris Sb red); 3 (C24H88Cl25N16O4Sb3; tris Sb yellow)] identifies crucial factors that control their emissive properties. The X-ray analysis reveals the structure (1-octahedral; 2-quadrangular pyramidal; 3-combination thereof) and the order of the extent of structural distortion as 1-3 MUCH LESS-THAN 2. The metal halide coordination environment asymmetry and its structure are observed to dictate PL emission energy (1-green; 2-red; 3-yellow) as supported by a qualitative Molecular Orbital scheme. The extent of structural distortion guides the observed Stokes shifts (1-165 nm; 2-290 nm; 3-200 nm; 1-3 \< 2). Interestingly, the extent of distortion is found to be well correlated with the observed PLQY (1-45\%; 2-6\%; 3-43\%; 1-3 \>\> 2). This report clearly demonstrates the structural tunability and the effect of the metal halide unit structure/distortion in shaping the emissive properties of 0D organic Sb(iii) halide hybrids.

}, issn = {2050-7526}, doi = {10.1039/d0tc03440a}, author = {Biswas, Anupam and Bakthavatsalam, Rangarajan and Mali, Bhupendra P. and Bahadur, Vir and Biswas, Chinmoy and Raavi, Sai Santosh Kumar and Gonnade, Rajesh G. and Kundu, Janardan} } @article {48141, title = {Monomeric magnesium catalyzed alkene and alkyne hydroboration}, journal = {Chemistry-A European Journal}, volume = {28}, year = {2022}, month = {OCT }, type = {Article}, abstract = {

In this work, two monomeric magnesium alkyl complexes (1 and 2) were prepared using bis(phosphino)carbazole framework and among them 1 has been used as a catalyst for hydroboration of alkenes and alkynes with pinacolborane (HBpin). A broad variety of aromatic and aliphatic alkenes and alkynes were efficiently reduced. Anti-Markovnikov regioselective hydroboration of alkenes and alkynes was achieved, which was confirmed by deuterium-labelling experiments. The work represents the first example of the use of magnesium in homogeneous catalytic hydroboration of alkene with broad substrate scope. Experimental mechanistic investigations and DFT calculations provided insights into the reaction mechanism. Finally, the hydroboration protocol was extended to terpenes.

}, keywords = {carbazole, Magnesium, monomeric complexes, phosphorous, X-ray Structure}, issn = {0947-6539}, doi = {10.1002/chem.202201896}, author = {Kumar, Rohit and Dutta, Sayan and Sharma, Vishal and Singh, Praval P. and Gonnade, Rajesh G. and Koley, Debasis and Sen, Sakya S.} }