Rabeprazole (RPZH) (available as rabeprazole sodium, RPZNa) is a proton pump inhibitor (PPI), wid... more Rabeprazole (RPZH) (available as rabeprazole sodium, RPZNa) is a proton pump inhibitor (PPI), widely used for the treatment of acid-related diseases in the stomach and duodenum. It is a weak base with pKa= 4.9 and show a strong ability to form complexes with transition and nontransition metal ions. Its complexes with Cu(II), Zn(II), Cd(II) and Hg(II) have been synthesized and characterized by solubility, melting point, metal content estimation, IR and UV-Visible spectral analysis, magnetic measurement, thermogravimetric analysis, differential scanning calorimetry and X-ray powder diffraction studies. On the basis of metal contents, the complexes have been formulated as [Cu(RPZ)(H2O)Cl], [Zn(RPZ)2], [Cd(RPZ)2].2H2O and [Hg(RPZ)2].H2O. Rabeprazole sodium (RPZNa) loses Na+ ion in solution yielding a monoanionic RPZ that behaves as a bidentate ligand and coordinates through C-N- and S=O groups with the divalent metal ion. Tetrahedral geometry of all complexes is proposed. Zn(II), Cd(II)...
Mixed ligand binuclear complexes of Cu(II) and Cd(II) with adenine (Ade) and 1,4-diazabicyclo[2.2... more Mixed ligand binuclear complexes of Cu(II) and Cd(II) with adenine (Ade) and 1,4-diazabicyclo[2.2.2]octane (DABCO) havebeen synthesized at a metal to ligands (M:L:L′) molar ratio of 1:1:1 in aqueous medium under ambient conditions. All synthesizedcomplexes are powdery solids of different colours, slightly soluble in hot water and decompose at high temperature. Characterizationof the complexes was accomplished using various analytical techniques, e.g. metal and chloride content analysis, Fourier transformspectrophotometer (FT-IR), UV-visible spectrophotometer, magnetic measurement, and thermal analyses. The metal and chloridecontents analyses of the complexes reveal to their stoichiometry [M2Cl2(Ade)2(H2O)2(DABCO)]Cl2 [M = Cu(II) or Cd(II)]. Analyticaldata suggests that they are homo metal symmetric binuclear complexes comprises of two [MCl(Ade)(H2O)] moieties in betweena DABCO molecule is N,N′-bridge bonded. The arrangements of the ligands around the metal centers are essentially te...
Complexes of divalent cobalt, copper and zinc with adenine were prepared and characterized. The c... more Complexes of divalent cobalt, copper and zinc with adenine were prepared and characterized. The complexes were formulated as [Co(C5H5N5)2Cl2].H2O, [Cu(C5H5N5)(H2O)3Cl2].H2O, and [Zn(C5H6N5)Cl3] on the basis of their metal and chloride contents. Their solubility, melting point, IR and UV-Visible spectra, magnetic and thermal properties, and conductivity were studied. The cyclic voltammetric study of only Cu(II) complex was also carried out.
The electrochemical redox behavior of transition metal ion Co2+ at different pH in acetate buffer... more The electrochemical redox behavior of transition metal ion Co2+ at different pH in acetate buffer solution has been investigated using cyclic voltammetry and differential pulse voltammetry at glassy carbon electrode (GCE). In cyclic voltammograms (CVs), Co2+ shows a pair of cathodic and a pair of anodic peak. The peak potential separation and peak current ratio reveals that the redox process of the redox couples, Co2+/Co+ and Co+/Co followed a quasi-reversible behavior and are two step one-electron transfer processes. The electrochemical processes are diffusion controlled. The nature of CV of Co2+ has greatly influenced by the potential scan rate and solution pH. With increasing scan rate both cathodic peaks shifted towards negative potential and first cathodic peak was eventually diminished. In the reverse direction, unexpected behavior such as distinguishable second anodic peak, identical heights of two anodic peaks, three humps like peaks and finally domination of second anodic p...
Guanine forms compounds with Cr(VI), Ag(I), Cd(II) and Hg(II) in acidic aqueous media. The compou... more Guanine forms compounds with Cr(VI), Ag(I), Cd(II) and Hg(II) in acidic aqueous media. The compounds are formulated as (C5H6N5O)2(Cr2O7).H2O, [Ag{(C5H6N5O)(NO3)}2](C5H6N5O)(NO3)2, [(C5H4N5O)2Cd](C5H6N5O)Cl and [(C5H4N5O)2Hg](C5H6N5O)Cl on the basis of their metal and chloride contents. Physico-chemical properties such as solubility, melting point, IR and UV-visible spectra, magnetic susceptibility, and thermal behavior of the compounds were studied. The composition of (C5H6N5O)2(Cr2O7).H2O was also investigated by continuous variation method. Keywords: Nucleic acids; Guaninium ions; Pyrimidine ring; Magnetic susceptibilities. DOI: http://dx.doi.org/10.3329/jbcs.v24i2.9699 Journal of Bangladesh Chemical Society, Vol. 24(2), 106-114, 2011
The electrochemical redox behavior of Cu(II) has been investigated at glassy carbon electrode (GC... more The electrochemical redox behavior of Cu(II) has been investigated at glassy carbon electrode (GCE) in Britton-Robinson (BR) buffer as well as in a mixture of BR buffer and potassium chloride media. It is apparent that BR buffer can act as a supporting electrolyte and modify the electrochemical behavior of Cu(II) ion in aqueous medium. In BR buffer medium, Cu(II) undergoes one two-electrons redox process, while in a mixture of BR buffer and KCl media it follows two one-electron electrochemical reaction routes. Because of the formation of hydrogen bridge bond between the supporting electrolyte and GCE surface, the Cu(II) ion follows Cu(II)/Cu(0) electrochemical reaction path, while in presence of KCl such a hydrogen bridge bond is not formed and it undergoes successive Cu(II)/Cu(I) and Cu(I)/Cu(0) electrode reaction processes. Moreover, the linear variation of peak current with the square root of scan rate indicates that the electrochemical redox processes are diffusion controlled. K...
The reaction of thiamine.HCl (ThHCl) with K2Cr2O7 has been studied in aqueous solution at room te... more The reaction of thiamine.HCl (ThHCl) with K2Cr2O7 has been studied in aqueous solution at room temperature. The compound obtained is ionic 1 : 1 in which thiamine is present as a cation and Cr2O7 2- as an anion. The chemical formula of the salt, (C12H18N4OS) (Cr2O7) (symbolically ThHCr2O7), has been established by elemental analysis, IR and UV/Vis spectra, magnetic measurement, thermal analysis, conductivity measurement, cyclic voltammetric study and X-ray diffraction analysis.DOI: http://dx.doi.org/10.3329/jbas.v35i1.7970Journal of Bangladesh Academy of Sciences, Vol.35, No.1, 51-59, 2011
The electrochemistry of Mn2+ at different pH (3.5-4.5) in acetate buffer solution has been invest... more The electrochemistry of Mn2+ at different pH (3.5-4.5) in acetate buffer solution has been investigated, using cyclic voltammetric method at glassy carbon electrode (GCE). Cyclic voltammograms (CVs) of Mn2+ show two cathodic and an anodic peaks over the entire investigated pH. The CVs of Mn2+ has also been performed in presence of proton pump inhibitors (PPIs) such as omeprazole, pantoprazole, esomeprazole and rabeprazole to elucidate the interaction of Mn2+ with the PPIs in acetate buffer solution. At the studied pH, a reasonably strong interaction was observed between Mn2+ and PPIs at different molar ratio of Mn2+ ion and PPIs. However, maximum interaction has been found at 1:2 molar ratio of Mn2+ and PPIs. This indicates the most suitable condition for the interaction between Mn2+ and PPIs. These results could allow insight into the interactions of metal ions with the PPIs. Dhaka Univ. J. Sci. 64(2): 115-120, 2016 (July)
The determination of the crystal structure of methyl 4,6-O-benzylidene-2,3-O-dibutylstannylene-α-... more The determination of the crystal structure of methyl 4,6-O-benzylidene-2,3-O-dibutylstannylene-α-D-glucopyranoside (1) was repeated from data collected at −70 °C because the previous assignment had a large R value (10.9%) and because this structure was the key link in assignment of structures of all stannylene acetals in solution. Crystals of 1 are orthorhombic, of space group P212121, with a = 12.479(2), b = 19.202(5), c = 19.654(6) Å, Z = 4, R = 0.0597 (Rw = 0.0612) for 3623 independent reflections with I > 3σ(I). Compound 1 is a dimer linked together by a four-membered 1,3-dioxa-2,4-distannetane ring containing the O-3 atoms from the two glucose units. Deviations from C2 symmetry are much smaller than reported earlier and lie mainly in the orientations of the butyl groups. The butyl groups are still significantly disordered at −70 °C. It is suggested that steric effects of these flexible butyl groups may be an important factor in the selectivity for dicoordinate oxygens previo...
Cobaloxime complexes of the type [CoCl(DMGH)2(L)], where DMGH = dimethylglyoxime monoanion, L = t... more Cobaloxime complexes of the type [CoCl(DMGH)2(L)], where DMGH = dimethylglyoxime monoanion, L = tri-ethanolamine and 1,10- phenanthroline, were synthesized. The compounds were formulated on the basis of cobalt and chloride contents, IR and UV-visible spectral analyses and magnetic moment measurement. Cyclic voltammetric technique was also employed to investigate the interaction between Co(II) and the ligands under studied.DOI: http://dx.doi.org/10.3329/dujs.v60i1.10345Dhaka Univ. J. Sci. 60(1): 97-101 2012 (January)
The complexes of Cu(II), Zn(II), Cd(II) and Hg(II) with adenine (AdeH) and uracil (UraH) have bee... more The complexes of Cu(II), Zn(II), Cd(II) and Hg(II) with adenine (AdeH) and uracil (UraH) have been synthesized and characterized by a combination of metal contents estimation, IR, UV-vis spectral data, thermogravimetric analysis (QSTG, TG and DSC) and magnetic susceptibility measurement. All the complexes are micro-crystalline, slightly soluble in water and decompose at high temperature. Both adenine and uracil deprotonated under experimental condition and then ligated to the metal ions as bidentate ligands through N(3) and N(9) of adeninato (Ade), and through N(3) and C(2)=O of uracilato (Ura) anions. On the basis of the metal contents, the complexes are formulated as [M(C5H4N5O)(C5H4N5)(H2O)2] [M = Cu(II), Zn(II) and Hg(II)] and [Cd(C5H4N5)(C4H3N2O2)(H2O)2].2H2O. The redox properties of copper and cadmium complexes were examined in aqueous solution by cyclic voltammetry. The voltammograms show quasi-reversible behavior for both the complexes. The X-ray powder diffraction study of ...
Plasma instabilities lead to exponentially growing charge density oscillations, which can generat... more Plasma instabilities lead to exponentially growing charge density oscillations, which can generate electromagnetic radiation at the same frequency. Current driven semiconductor nanostructures can develop THz collective oscillations and serve as radiation sources in that range.The basic criterion for plasma instabilities was established [1] to be the resonant interaction of an emissive plasmon mode with an absorptive plasmon mode.Scenarios are presented where this phenomenon can be realized in a high density low current regime.A special case is a reservoir (an absorptive mode) with an adjoining quantum well that harbors a population inverted pair of subbands (the emissive mode). [1].P.Bakshi and K.Kempa,Condensed Matter Theories,12,p.399-412,(1997). Work supported by US Army Research Office.
Rabeprazole (RPZH) (available as rabeprazole sodium, RPZNa) is a proton pump inhibitor (PPI), wid... more Rabeprazole (RPZH) (available as rabeprazole sodium, RPZNa) is a proton pump inhibitor (PPI), widely used for the treatment of acid-related diseases in the stomach and duodenum. It is a weak base with pKa= 4.9 and show a strong ability to form complexes with transition and nontransition metal ions. Its complexes with Cu(II), Zn(II), Cd(II) and Hg(II) have been synthesized and characterized by solubility, melting point, metal content estimation, IR and UV-Visible spectral analysis, magnetic measurement, thermogravimetric analysis, differential scanning calorimetry and X-ray powder diffraction studies. On the basis of metal contents, the complexes have been formulated as [Cu(RPZ)(H2O)Cl], [Zn(RPZ)2], [Cd(RPZ)2].2H2O and [Hg(RPZ)2].H2O. Rabeprazole sodium (RPZNa) loses Na+ ion in solution yielding a monoanionic RPZ that behaves as a bidentate ligand and coordinates through C-N- and S=O groups with the divalent metal ion. Tetrahedral geometry of all complexes is proposed. Zn(II), Cd(II)...
Mixed ligand binuclear complexes of Cu(II) and Cd(II) with adenine (Ade) and 1,4-diazabicyclo[2.2... more Mixed ligand binuclear complexes of Cu(II) and Cd(II) with adenine (Ade) and 1,4-diazabicyclo[2.2.2]octane (DABCO) havebeen synthesized at a metal to ligands (M:L:L′) molar ratio of 1:1:1 in aqueous medium under ambient conditions. All synthesizedcomplexes are powdery solids of different colours, slightly soluble in hot water and decompose at high temperature. Characterizationof the complexes was accomplished using various analytical techniques, e.g. metal and chloride content analysis, Fourier transformspectrophotometer (FT-IR), UV-visible spectrophotometer, magnetic measurement, and thermal analyses. The metal and chloridecontents analyses of the complexes reveal to their stoichiometry [M2Cl2(Ade)2(H2O)2(DABCO)]Cl2 [M = Cu(II) or Cd(II)]. Analyticaldata suggests that they are homo metal symmetric binuclear complexes comprises of two [MCl(Ade)(H2O)] moieties in betweena DABCO molecule is N,N′-bridge bonded. The arrangements of the ligands around the metal centers are essentially te...
Complexes of divalent cobalt, copper and zinc with adenine were prepared and characterized. The c... more Complexes of divalent cobalt, copper and zinc with adenine were prepared and characterized. The complexes were formulated as [Co(C5H5N5)2Cl2].H2O, [Cu(C5H5N5)(H2O)3Cl2].H2O, and [Zn(C5H6N5)Cl3] on the basis of their metal and chloride contents. Their solubility, melting point, IR and UV-Visible spectra, magnetic and thermal properties, and conductivity were studied. The cyclic voltammetric study of only Cu(II) complex was also carried out.
The electrochemical redox behavior of transition metal ion Co2+ at different pH in acetate buffer... more The electrochemical redox behavior of transition metal ion Co2+ at different pH in acetate buffer solution has been investigated using cyclic voltammetry and differential pulse voltammetry at glassy carbon electrode (GCE). In cyclic voltammograms (CVs), Co2+ shows a pair of cathodic and a pair of anodic peak. The peak potential separation and peak current ratio reveals that the redox process of the redox couples, Co2+/Co+ and Co+/Co followed a quasi-reversible behavior and are two step one-electron transfer processes. The electrochemical processes are diffusion controlled. The nature of CV of Co2+ has greatly influenced by the potential scan rate and solution pH. With increasing scan rate both cathodic peaks shifted towards negative potential and first cathodic peak was eventually diminished. In the reverse direction, unexpected behavior such as distinguishable second anodic peak, identical heights of two anodic peaks, three humps like peaks and finally domination of second anodic p...
Guanine forms compounds with Cr(VI), Ag(I), Cd(II) and Hg(II) in acidic aqueous media. The compou... more Guanine forms compounds with Cr(VI), Ag(I), Cd(II) and Hg(II) in acidic aqueous media. The compounds are formulated as (C5H6N5O)2(Cr2O7).H2O, [Ag{(C5H6N5O)(NO3)}2](C5H6N5O)(NO3)2, [(C5H4N5O)2Cd](C5H6N5O)Cl and [(C5H4N5O)2Hg](C5H6N5O)Cl on the basis of their metal and chloride contents. Physico-chemical properties such as solubility, melting point, IR and UV-visible spectra, magnetic susceptibility, and thermal behavior of the compounds were studied. The composition of (C5H6N5O)2(Cr2O7).H2O was also investigated by continuous variation method. Keywords: Nucleic acids; Guaninium ions; Pyrimidine ring; Magnetic susceptibilities. DOI: http://dx.doi.org/10.3329/jbcs.v24i2.9699 Journal of Bangladesh Chemical Society, Vol. 24(2), 106-114, 2011
The electrochemical redox behavior of Cu(II) has been investigated at glassy carbon electrode (GC... more The electrochemical redox behavior of Cu(II) has been investigated at glassy carbon electrode (GCE) in Britton-Robinson (BR) buffer as well as in a mixture of BR buffer and potassium chloride media. It is apparent that BR buffer can act as a supporting electrolyte and modify the electrochemical behavior of Cu(II) ion in aqueous medium. In BR buffer medium, Cu(II) undergoes one two-electrons redox process, while in a mixture of BR buffer and KCl media it follows two one-electron electrochemical reaction routes. Because of the formation of hydrogen bridge bond between the supporting electrolyte and GCE surface, the Cu(II) ion follows Cu(II)/Cu(0) electrochemical reaction path, while in presence of KCl such a hydrogen bridge bond is not formed and it undergoes successive Cu(II)/Cu(I) and Cu(I)/Cu(0) electrode reaction processes. Moreover, the linear variation of peak current with the square root of scan rate indicates that the electrochemical redox processes are diffusion controlled. K...
The reaction of thiamine.HCl (ThHCl) with K2Cr2O7 has been studied in aqueous solution at room te... more The reaction of thiamine.HCl (ThHCl) with K2Cr2O7 has been studied in aqueous solution at room temperature. The compound obtained is ionic 1 : 1 in which thiamine is present as a cation and Cr2O7 2- as an anion. The chemical formula of the salt, (C12H18N4OS) (Cr2O7) (symbolically ThHCr2O7), has been established by elemental analysis, IR and UV/Vis spectra, magnetic measurement, thermal analysis, conductivity measurement, cyclic voltammetric study and X-ray diffraction analysis.DOI: http://dx.doi.org/10.3329/jbas.v35i1.7970Journal of Bangladesh Academy of Sciences, Vol.35, No.1, 51-59, 2011
The electrochemistry of Mn2+ at different pH (3.5-4.5) in acetate buffer solution has been invest... more The electrochemistry of Mn2+ at different pH (3.5-4.5) in acetate buffer solution has been investigated, using cyclic voltammetric method at glassy carbon electrode (GCE). Cyclic voltammograms (CVs) of Mn2+ show two cathodic and an anodic peaks over the entire investigated pH. The CVs of Mn2+ has also been performed in presence of proton pump inhibitors (PPIs) such as omeprazole, pantoprazole, esomeprazole and rabeprazole to elucidate the interaction of Mn2+ with the PPIs in acetate buffer solution. At the studied pH, a reasonably strong interaction was observed between Mn2+ and PPIs at different molar ratio of Mn2+ ion and PPIs. However, maximum interaction has been found at 1:2 molar ratio of Mn2+ and PPIs. This indicates the most suitable condition for the interaction between Mn2+ and PPIs. These results could allow insight into the interactions of metal ions with the PPIs. Dhaka Univ. J. Sci. 64(2): 115-120, 2016 (July)
The determination of the crystal structure of methyl 4,6-O-benzylidene-2,3-O-dibutylstannylene-α-... more The determination of the crystal structure of methyl 4,6-O-benzylidene-2,3-O-dibutylstannylene-α-D-glucopyranoside (1) was repeated from data collected at −70 °C because the previous assignment had a large R value (10.9%) and because this structure was the key link in assignment of structures of all stannylene acetals in solution. Crystals of 1 are orthorhombic, of space group P212121, with a = 12.479(2), b = 19.202(5), c = 19.654(6) Å, Z = 4, R = 0.0597 (Rw = 0.0612) for 3623 independent reflections with I > 3σ(I). Compound 1 is a dimer linked together by a four-membered 1,3-dioxa-2,4-distannetane ring containing the O-3 atoms from the two glucose units. Deviations from C2 symmetry are much smaller than reported earlier and lie mainly in the orientations of the butyl groups. The butyl groups are still significantly disordered at −70 °C. It is suggested that steric effects of these flexible butyl groups may be an important factor in the selectivity for dicoordinate oxygens previo...
Cobaloxime complexes of the type [CoCl(DMGH)2(L)], where DMGH = dimethylglyoxime monoanion, L = t... more Cobaloxime complexes of the type [CoCl(DMGH)2(L)], where DMGH = dimethylglyoxime monoanion, L = tri-ethanolamine and 1,10- phenanthroline, were synthesized. The compounds were formulated on the basis of cobalt and chloride contents, IR and UV-visible spectral analyses and magnetic moment measurement. Cyclic voltammetric technique was also employed to investigate the interaction between Co(II) and the ligands under studied.DOI: http://dx.doi.org/10.3329/dujs.v60i1.10345Dhaka Univ. J. Sci. 60(1): 97-101 2012 (January)
The complexes of Cu(II), Zn(II), Cd(II) and Hg(II) with adenine (AdeH) and uracil (UraH) have bee... more The complexes of Cu(II), Zn(II), Cd(II) and Hg(II) with adenine (AdeH) and uracil (UraH) have been synthesized and characterized by a combination of metal contents estimation, IR, UV-vis spectral data, thermogravimetric analysis (QSTG, TG and DSC) and magnetic susceptibility measurement. All the complexes are micro-crystalline, slightly soluble in water and decompose at high temperature. Both adenine and uracil deprotonated under experimental condition and then ligated to the metal ions as bidentate ligands through N(3) and N(9) of adeninato (Ade), and through N(3) and C(2)=O of uracilato (Ura) anions. On the basis of the metal contents, the complexes are formulated as [M(C5H4N5O)(C5H4N5)(H2O)2] [M = Cu(II), Zn(II) and Hg(II)] and [Cd(C5H4N5)(C4H3N2O2)(H2O)2].2H2O. The redox properties of copper and cadmium complexes were examined in aqueous solution by cyclic voltammetry. The voltammograms show quasi-reversible behavior for both the complexes. The X-ray powder diffraction study of ...
Plasma instabilities lead to exponentially growing charge density oscillations, which can generat... more Plasma instabilities lead to exponentially growing charge density oscillations, which can generate electromagnetic radiation at the same frequency. Current driven semiconductor nanostructures can develop THz collective oscillations and serve as radiation sources in that range.The basic criterion for plasma instabilities was established [1] to be the resonant interaction of an emissive plasmon mode with an absorptive plasmon mode.Scenarios are presented where this phenomenon can be realized in a high density low current regime.A special case is a reservoir (an absorptive mode) with an adjoining quantum well that harbors a population inverted pair of subbands (the emissive mode). [1].P.Bakshi and K.Kempa,Condensed Matter Theories,12,p.399-412,(1997). Work supported by US Army Research Office.
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