Prof. M V Rajasekharan | University of Hyderabad (original) (raw)
Papers by Prof. M V Rajasekharan
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Molecular Crystals and Liquid Crystals, 1980
ABSTRACT
ChemistrySelect, 2019
A series of thirteen complexes which may be formally considered as assembled from Cu(bpy) 2 (NO 3... more A series of thirteen complexes which may be formally considered as assembled from Cu(bpy) 2 (NO 3) 2 and Ln(NO 3) 3 (Ln = LaÀ Yb excluding Pm, bpy = 2,2'-bipyridine) have been characterized. The crystals may be grouped into four classes: A, [Cu 2 (bpy) 4 (μ-NO 3)][Ln(NO 3) 6 ] (Ln = LaÀ Nd); B, [Cu (bpy) 2 (NO 3)] 2 [Ln(NO 3) 4 (OH 2) 2 ](NO 3) (Ln = SmÀ Dy); C, [Cu (bpy) 2 (NO 3)] 2 [Ln(NO 3) 5 ] (Ln = HoÀ Tm); D, [Cu(bpy) 2 (NO 3)] 2 [Ln (NO 3) 3 (OH 2) 3 ](NO 3) 2 ⋅2H 2 O (Ln = Yb). The coordination numbers of the nitrato or aquonitrato lanthanide anions range from 9 to 12. The dinuclear cation in Class A having a linear monoatomic nitrate bridge is new and is seen to produce weak antiferromagnetic coupling in these compounds. The other classes contain distortion isomers of [Cu(bpy) 2 NO 3 ] +. The structural trends are analysed in terms of lanthanide contraction and non-covalent interactions in the crystals. EPR and electronic spectral characteristics are discussed for the four classes of compounds.
European Journal of Inorganic Chemistry, 2014
Alkaline-earth (AE)/cerium(III)-based heterometallic coordination compounds of the biologically i... more Alkaline-earth (AE)/cerium(III)-based heterometallic coordination compounds of the biologically important ligand dipicolinic acid (dipicH2), namely [Mg(H2O)6]2[Ce(dipic)3][Ce(dipic)2(H2O)3]·2H2O (1), [Ca3(H2O)12Ce2(dipic)6]·6H2O (2), [Sr3(H2O)16Ce2(dipic)6]·4H2O (3) and [Ba2(H2O)7Ce(dipic)3NO3]·H2O (4), have been obtained by the reduction of an aqueous solution of (NH4)2Ce(NO3)6·6H2O in the presence of dipicH2 and alkaline-earth oxides or carbonates. This series demonstrates the role of AE ions in controlling the topology of coordination networks based on the [Ce(dipic)3]3– anion. Compound 1 is a zero-dimensional ionic compound, the crystal structure of compound 2 is based on a mixed four-connected 3D network, compound 3 presents ladder-shaped chains running along a crystallographic axis, and layers of squeezed CeBa6 pentagonal pyramids interconnected by nitrates generate a mixed five- and six-connected network in 4. A thermal analysis showed that all four compounds exhibit reversible water-uptake capacity and the basic nature of the frameworks could be intact up to at least 120 °C.
Acta Crystallographica Section C Crystal Structure Communications, 1990
ChemistrySelect, 2016
Heterometallic coordination polymers having the general formula [A 3 (H 2 O) n Ce(dipic) 3 ]•mH 2... more Heterometallic coordination polymers having the general formula [A 3 (H 2 O) n Ce(dipic) 3 ]•mH 2 O, where A denotes an alkali metal ion (Li-Cs), have been obtained by reacting an aqueous solution of Ce(NO 3) 3 •6H 2 O with alkali hydroxides in presence of dipicH 2. Ce(dipic) 3 3ion functions as a metallo-ligand by linking the alkali ions. While the lightest alkali ion forms a 2D coordination network (1, n = 6, m = 3), all others form 3D networks (Na: 2, n = 8, m = 7; K: 3, n = 9, m = 3; Rb: 4 and 5, n = 6, m = 2; Cs: 6, n = 6, m = 3). The structure of compound 2 was inferred from the isomorphous NaÀGd compound (7) which formed better quality crystals. Remarkably, both Na and K networks are built around alkali ion-water chains. In the case of the three lighter alkali ions, the lattice water molecules are assembled into water clusters: tetramer (Li); acyclic heptamer (Na); water tape (K). X-ray powder diffraction studies show that the hydrated structures could be regenerated by exposure of the dehydrated samples to moisture in the case of Li, Na and K, but not for Rb and Cs.
Physical Review B, 1990
Long-range exchange interaction in (2, 2'-bipyridine-3, 3'-dicarboxylic acid)dichlorocopper(II) m... more Long-range exchange interaction in (2, 2'-bipyridine-3, 3'-dicarboxylic acid)dichlorocopper(II) monohydrate via lattice water: Single-crystal EPR studies
Computers & Chemistry, 1996
ABSTRACT A FORTRAN program, SUSCEP.FOR, was developed for the fitting of the magnetic susceptibil... more ABSTRACT A FORTRAN program, SUSCEP.FOR, was developed for the fitting of the magnetic susceptibility curve measured as a function of temperature into a selected expression. It can be executed on an IBM PC compatible. The simplex method was used for least squares fit of a wide range of expressions for various spin systems. The calculated and observed susceptibility data are compared graphically for choosing initial values of unknown parameters and to examine the final fit. The input is given interactively through menus and the output is saved on disk file. Standard deviations of parameters are estimated. SUSCEP.FOR includes the following functions and the expressions resulted by linear combinations among them: (1) Curie law, (2) ions with zero-field splitting term (D) for 1 ⩽ S ⩽ 52, (3) Ising equation, (4) Bleaney-Bower equation, (5) magnetization equation for S = 12dimer, (6) Bonner-Fisher equation, (7) modified Bonner-Fisher equation, (8) dimers with a variety of values for S1 and S2, (9) a few other selected functions from the literature, (10) a constant as a correction term. The program also considers molecular field correction for functions 2–9 and the Weiss constant for the Curie law. It provides a routine for user-specified function which can be modified to user requirements. Also there is provision to add more functions to enhance the capability. The program can handle up to 300 data points and 12 parameters. These limits can be increased if necessary by modifying the array dimensions.
European Journal of Inorganic Chemistry, 2015
Two new iodobromides [I 2 Br 6 2-(analogue of I 8 2and Br 8 2-) and IBr 4-(analogue of Br 5 and I... more Two new iodobromides [I 2 Br 6 2-(analogue of I 8 2and Br 8 2-) and IBr 4-(analogue of Br 5 and I 2 Br 3-)] and new chains formed from Br 3-, Br 2 and IBr 4 have been obtained in three compounds all containing the same Cu II tris-chelate cation Cu(dafone) 3 2+ {[Cu(dafone) 3 ](Br 3)(Br 5) (1), [Cu(dafone) 3 ]-(Br 5)(Br 8) 0.5 •CH 3 CN (2) and [Cu(dafone) 3 ](IBr 4)(I 2 Br 6) 0.5 •-[a
Polyhedron, 2015
Abstract Two new diaquo-bridged dicopper(II) complexes are obtained by reacting Cu(II) nitrate wi... more Abstract Two new diaquo-bridged dicopper(II) complexes are obtained by reacting Cu(II) nitrate with isonicotinic acid and either 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen). They are formulated as [Cu2(μ-OH2)2(L)2(INH)2(NO3)2](NO3)2 where L = bpy (1), phen (2) and INH = zwitterion of isonicotinic acid. Both the complexes were characterized by single crystal X-ray diffraction analysis, variable temperature magnetic susceptibility measurements and EPR spectroscopy. The complexes consist a dinuclear cation, [Cu(OH2)2Cu]+4 at its core in which the water molecules function as unsymmetrical bridges between Cu(II) octahedra in the equatorial–axial mode. The variable temperature (3–300 K) magnetic susceptibility measurements suggest weak ferromagnetic coupling in the dicopper(II) cation with 2J = 3.52 and 1.80 cm−1 respectively for 1 and 2. Both compounds give triplet state EPR with similar zero-field splitting parameter, D = 0.034 cm−1 for 1 and 0.038 cm−1 for 2.
European Journal of Medicinal Chemistry, 2015
Decaprenylphosphoryl-b-D-ribose 20-epimerase (DprE1) is a potential drug target for development o... more Decaprenylphosphoryl-b-D-ribose 20-epimerase (DprE1) is a potential drug target for development of antitubercular agents. Structure based drug discovery approach yielded twenty novel derivatives of benzothiazolylpyrimidine-5-carboxamides (7aet) which were synthesised by three component one pot reaction involving benzothiazolyl oxobutanamide, thiourea and substituted aromatic benzaldehydes. These derivatives were evaluated for antitubercular activity to determine MIC and compound 7a, 7e, 7f and 7o were found to be potentially active against Mycobacterium tuberculosis (H 37 Rv). Log P of these compounds was found to be between 2.0 and 3.0 making them suitable for oral dosing. DprE1 selectivity and pharmacokinetic studies were carried out for these compounds of which 7a and 7o were found to be highly selective and bioavailability was found to be above 52% by oral dose. Crystal structure of 7a was studied and molecular packing was determined, it exhibited a triclinic crystal lattice arrangement having hydrogen bonded dimeric arrangement. Drug receptor interactions were studied which exhibited docking in the active site of receptor with hydrogen bonding, hydrophobic interactions, vdW interactions with amino acid residues such as Cys387, Asn385, Lys418, Tyr314, Gln334 and Lys367 respectively. 3D QSAR analysis was carried out by kNN-MFA method to determine and develop theoretical model, best suitable model was found to be based on Simulated Annealing k-Neariest Neighbour Molecular Field Analysis (SA kNN-MFA). The model provided with hydrophobic descriptors in positive side indicating the need of bulky groups, steric and electronegative descriptors in negative coordinates hints with contribution by the electronegative substitutions as favourable and desirable moieties for enhancing the activity. The q 2 , q 2 _se and Pred_r 2 se were found to be 0.5000, 0.6404 and 1.0094 respectively. A pharmacophore model was generated which suggested for necessity of aromatic, aliphatic carbon centre and hydrogen bond donor for development of newer DprE1 selective inhibitors.
![Research paper thumbnail of Complexes of AgIwith cationic ligands: bis[(pyridylmethyl)ammonio]silver(I) salts](https://attachments.academia-assets.com/103764088/thumbnails/1.jpg)
](Acta Crystallographica Section C Crystal Structure Communications, 2001
Symmetry codes: (i) x À 1Y yY z; (ii) x À 1Y 1 yY z; (iii) ÀxY 1 À yY Àz; (iv) 1 xY y À 1Y z; (v)... more Symmetry codes: (i) x À 1Y yY z; (ii) x À 1Y 1 yY z; (iii) ÀxY 1 À yY Àz; (iv) 1 xY y À 1Y z; (v) 1 À xY ÀyY Àz; (vi) 1 À xY 2 À yY Àz; (vii) 1 À xY 1 À yY Àz; (viii) 1 xY yY z.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Molecular Crystals and Liquid Crystals, 1980
ABSTRACT
ChemistrySelect, 2019
A series of thirteen complexes which may be formally considered as assembled from Cu(bpy) 2 (NO 3... more A series of thirteen complexes which may be formally considered as assembled from Cu(bpy) 2 (NO 3) 2 and Ln(NO 3) 3 (Ln = LaÀ Yb excluding Pm, bpy = 2,2'-bipyridine) have been characterized. The crystals may be grouped into four classes: A, [Cu 2 (bpy) 4 (μ-NO 3)][Ln(NO 3) 6 ] (Ln = LaÀ Nd); B, [Cu (bpy) 2 (NO 3)] 2 [Ln(NO 3) 4 (OH 2) 2 ](NO 3) (Ln = SmÀ Dy); C, [Cu (bpy) 2 (NO 3)] 2 [Ln(NO 3) 5 ] (Ln = HoÀ Tm); D, [Cu(bpy) 2 (NO 3)] 2 [Ln (NO 3) 3 (OH 2) 3 ](NO 3) 2 ⋅2H 2 O (Ln = Yb). The coordination numbers of the nitrato or aquonitrato lanthanide anions range from 9 to 12. The dinuclear cation in Class A having a linear monoatomic nitrate bridge is new and is seen to produce weak antiferromagnetic coupling in these compounds. The other classes contain distortion isomers of [Cu(bpy) 2 NO 3 ] +. The structural trends are analysed in terms of lanthanide contraction and non-covalent interactions in the crystals. EPR and electronic spectral characteristics are discussed for the four classes of compounds.
European Journal of Inorganic Chemistry, 2014
Alkaline-earth (AE)/cerium(III)-based heterometallic coordination compounds of the biologically i... more Alkaline-earth (AE)/cerium(III)-based heterometallic coordination compounds of the biologically important ligand dipicolinic acid (dipicH2), namely [Mg(H2O)6]2[Ce(dipic)3][Ce(dipic)2(H2O)3]·2H2O (1), [Ca3(H2O)12Ce2(dipic)6]·6H2O (2), [Sr3(H2O)16Ce2(dipic)6]·4H2O (3) and [Ba2(H2O)7Ce(dipic)3NO3]·H2O (4), have been obtained by the reduction of an aqueous solution of (NH4)2Ce(NO3)6·6H2O in the presence of dipicH2 and alkaline-earth oxides or carbonates. This series demonstrates the role of AE ions in controlling the topology of coordination networks based on the [Ce(dipic)3]3– anion. Compound 1 is a zero-dimensional ionic compound, the crystal structure of compound 2 is based on a mixed four-connected 3D network, compound 3 presents ladder-shaped chains running along a crystallographic axis, and layers of squeezed CeBa6 pentagonal pyramids interconnected by nitrates generate a mixed five- and six-connected network in 4. A thermal analysis showed that all four compounds exhibit reversible water-uptake capacity and the basic nature of the frameworks could be intact up to at least 120 °C.
Acta Crystallographica Section C Crystal Structure Communications, 1990
ChemistrySelect, 2016
Heterometallic coordination polymers having the general formula [A 3 (H 2 O) n Ce(dipic) 3 ]•mH 2... more Heterometallic coordination polymers having the general formula [A 3 (H 2 O) n Ce(dipic) 3 ]•mH 2 O, where A denotes an alkali metal ion (Li-Cs), have been obtained by reacting an aqueous solution of Ce(NO 3) 3 •6H 2 O with alkali hydroxides in presence of dipicH 2. Ce(dipic) 3 3ion functions as a metallo-ligand by linking the alkali ions. While the lightest alkali ion forms a 2D coordination network (1, n = 6, m = 3), all others form 3D networks (Na: 2, n = 8, m = 7; K: 3, n = 9, m = 3; Rb: 4 and 5, n = 6, m = 2; Cs: 6, n = 6, m = 3). The structure of compound 2 was inferred from the isomorphous NaÀGd compound (7) which formed better quality crystals. Remarkably, both Na and K networks are built around alkali ion-water chains. In the case of the three lighter alkali ions, the lattice water molecules are assembled into water clusters: tetramer (Li); acyclic heptamer (Na); water tape (K). X-ray powder diffraction studies show that the hydrated structures could be regenerated by exposure of the dehydrated samples to moisture in the case of Li, Na and K, but not for Rb and Cs.
Physical Review B, 1990
Long-range exchange interaction in (2, 2'-bipyridine-3, 3'-dicarboxylic acid)dichlorocopper(II) m... more Long-range exchange interaction in (2, 2'-bipyridine-3, 3'-dicarboxylic acid)dichlorocopper(II) monohydrate via lattice water: Single-crystal EPR studies
Computers & Chemistry, 1996
ABSTRACT A FORTRAN program, SUSCEP.FOR, was developed for the fitting of the magnetic susceptibil... more ABSTRACT A FORTRAN program, SUSCEP.FOR, was developed for the fitting of the magnetic susceptibility curve measured as a function of temperature into a selected expression. It can be executed on an IBM PC compatible. The simplex method was used for least squares fit of a wide range of expressions for various spin systems. The calculated and observed susceptibility data are compared graphically for choosing initial values of unknown parameters and to examine the final fit. The input is given interactively through menus and the output is saved on disk file. Standard deviations of parameters are estimated. SUSCEP.FOR includes the following functions and the expressions resulted by linear combinations among them: (1) Curie law, (2) ions with zero-field splitting term (D) for 1 ⩽ S ⩽ 52, (3) Ising equation, (4) Bleaney-Bower equation, (5) magnetization equation for S = 12dimer, (6) Bonner-Fisher equation, (7) modified Bonner-Fisher equation, (8) dimers with a variety of values for S1 and S2, (9) a few other selected functions from the literature, (10) a constant as a correction term. The program also considers molecular field correction for functions 2–9 and the Weiss constant for the Curie law. It provides a routine for user-specified function which can be modified to user requirements. Also there is provision to add more functions to enhance the capability. The program can handle up to 300 data points and 12 parameters. These limits can be increased if necessary by modifying the array dimensions.
European Journal of Inorganic Chemistry, 2015
Two new iodobromides [I 2 Br 6 2-(analogue of I 8 2and Br 8 2-) and IBr 4-(analogue of Br 5 and I... more Two new iodobromides [I 2 Br 6 2-(analogue of I 8 2and Br 8 2-) and IBr 4-(analogue of Br 5 and I 2 Br 3-)] and new chains formed from Br 3-, Br 2 and IBr 4 have been obtained in three compounds all containing the same Cu II tris-chelate cation Cu(dafone) 3 2+ {[Cu(dafone) 3 ](Br 3)(Br 5) (1), [Cu(dafone) 3 ]-(Br 5)(Br 8) 0.5 •CH 3 CN (2) and [Cu(dafone) 3 ](IBr 4)(I 2 Br 6) 0.5 •-[a
Polyhedron, 2015
Abstract Two new diaquo-bridged dicopper(II) complexes are obtained by reacting Cu(II) nitrate wi... more Abstract Two new diaquo-bridged dicopper(II) complexes are obtained by reacting Cu(II) nitrate with isonicotinic acid and either 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen). They are formulated as [Cu2(μ-OH2)2(L)2(INH)2(NO3)2](NO3)2 where L = bpy (1), phen (2) and INH = zwitterion of isonicotinic acid. Both the complexes were characterized by single crystal X-ray diffraction analysis, variable temperature magnetic susceptibility measurements and EPR spectroscopy. The complexes consist a dinuclear cation, [Cu(OH2)2Cu]+4 at its core in which the water molecules function as unsymmetrical bridges between Cu(II) octahedra in the equatorial–axial mode. The variable temperature (3–300 K) magnetic susceptibility measurements suggest weak ferromagnetic coupling in the dicopper(II) cation with 2J = 3.52 and 1.80 cm−1 respectively for 1 and 2. Both compounds give triplet state EPR with similar zero-field splitting parameter, D = 0.034 cm−1 for 1 and 0.038 cm−1 for 2.
European Journal of Medicinal Chemistry, 2015
Decaprenylphosphoryl-b-D-ribose 20-epimerase (DprE1) is a potential drug target for development o... more Decaprenylphosphoryl-b-D-ribose 20-epimerase (DprE1) is a potential drug target for development of antitubercular agents. Structure based drug discovery approach yielded twenty novel derivatives of benzothiazolylpyrimidine-5-carboxamides (7aet) which were synthesised by three component one pot reaction involving benzothiazolyl oxobutanamide, thiourea and substituted aromatic benzaldehydes. These derivatives were evaluated for antitubercular activity to determine MIC and compound 7a, 7e, 7f and 7o were found to be potentially active against Mycobacterium tuberculosis (H 37 Rv). Log P of these compounds was found to be between 2.0 and 3.0 making them suitable for oral dosing. DprE1 selectivity and pharmacokinetic studies were carried out for these compounds of which 7a and 7o were found to be highly selective and bioavailability was found to be above 52% by oral dose. Crystal structure of 7a was studied and molecular packing was determined, it exhibited a triclinic crystal lattice arrangement having hydrogen bonded dimeric arrangement. Drug receptor interactions were studied which exhibited docking in the active site of receptor with hydrogen bonding, hydrophobic interactions, vdW interactions with amino acid residues such as Cys387, Asn385, Lys418, Tyr314, Gln334 and Lys367 respectively. 3D QSAR analysis was carried out by kNN-MFA method to determine and develop theoretical model, best suitable model was found to be based on Simulated Annealing k-Neariest Neighbour Molecular Field Analysis (SA kNN-MFA). The model provided with hydrophobic descriptors in positive side indicating the need of bulky groups, steric and electronegative descriptors in negative coordinates hints with contribution by the electronegative substitutions as favourable and desirable moieties for enhancing the activity. The q 2 , q 2 _se and Pred_r 2 se were found to be 0.5000, 0.6404 and 1.0094 respectively. A pharmacophore model was generated which suggested for necessity of aromatic, aliphatic carbon centre and hydrogen bond donor for development of newer DprE1 selective inhibitors.
Acta Crystallographica Section C Crystal Structure Communications, 2001
Symmetry codes: (i) x À 1Y yY z; (ii) x À 1Y 1 yY z; (iii) ÀxY 1 À yY Àz; (iv) 1 xY y À 1Y z; (v)... more Symmetry codes: (i) x À 1Y yY z; (ii) x À 1Y 1 yY z; (iii) ÀxY 1 À yY Àz; (iv) 1 xY y À 1Y z; (v) 1 À xY ÀyY Àz; (vi) 1 À xY 2 À yY Àz; (vii) 1 À xY 1 À yY Àz; (viii) 1 xY yY z.