Reama George | Obafemi Awolowo University,Ile-Ife,Nigeria (original) (raw)

Papers by Reama George

Research paper thumbnail of A DFT/TD-DFT study on the possible replacement of Ru(II) with Fe(II) in phthalocyanine-based dye-sensitized solar cells

Research paper thumbnail of Characterization of porphyrin nanorods on fluorine doped tin oxide glass sheet

Journal of Porphyrins and Phthalocyanines, 2015

Porphyrin nanorods (PNR) have been fabricated by electrostatic self-assembly of two oppositely ch... more Porphyrin nanorods (PNR) have been fabricated by electrostatic self-assembly of two oppositely charged porphyrin molecules. The free base meso-tetra-(4-phenylsulphonate) porphyrin (TPPS[Formula: see text] served as negatively charged counterpart for the positively charged metallo meso-tetra(4-[Formula: see text]-methylpyridyl) porphyrins (MTM’PyP) with either Sn, Co, Mn or In as central metal M. Films of PNR were prepared on fluorine doped tin oxide glass sheets (FTO) by using a drop-dry method. The electronic spectra revealed J-aggregation of the charged molecules for the colloid PNR as well as for the films. Transmission electron microscopy confirmed the formation of porphyrin nanorods. The laser microscope and scanning electron microscope (SEM) images of the PNR/FTO films showed the formation of three kinds of structures in the films which consist of differently branched or linear needles with their main axis grown in the direction of the solvent flow during preparation. During c...

Research paper thumbnail of Enhanced triplet state yields in aqueous media of asymmetric zinc phthalocyanines when conjugated to silver nanoflowers

Research paper thumbnail of Phytoremediation of Lindane and Dieldrin: A Screening Study

Research paper thumbnail of Absorbance and Fluorescence Studies on Porphyrin Nanostructures (PNR) as Light Harvesters in Dye Sensitized Solar Cells

Porphyrin nanorods (PNR) were fabricated by electrostatic self-assembly of two oppositely charge ... more Porphyrin nanorods (PNR) were fabricated by electrostatic self-assembly of two oppositely charge molecules and the compounds used were free base meso-tetra-(4-sulphonatephenyl) porphyrin (H2TPPS44-) and metallo meso-tetra (4-N-methylpyridyl) porphyrin (MTMPyP4+) (M = Sn, Mn, Co, In). The aim of this work was to study some photophysical properties of PNR for application as light harvester in dye sensitized solar cells. These properties include absorbance, fluorescence, and fluorescence quantum yield and lifetime. The results of Transmission Electron Microscope (TEM) images showed the formation of nanorods. Electronic Spectra of the PNR revealed J-aggregation bands at 492 nm and accompanied by a band at 712 nm. All the porphyrin nanostructures produced fluorescence at 670 nm when excited at 430 nm and each spectrum had a hidden band at 730 nm. The fluorescence quantum yields were low but deconvolution of the bi-exponential decay curves showed the existence of two species with lifetime...

Research paper thumbnail of Spectroscopic studies of nanostructures of negatively charged free base porphyrin and positively charged tin porphyrins

Polyhedron, 2010

... Medicinal Chemistry and Nanotechnology and Rhodes University. Reama George thanks Third World... more ... Medicinal Chemistry and Nanotechnology and Rhodes University. Reama George thanks Third World Organization of Women in Science (TWOWS) for a bursary. References. [1] HL Anderson, Chem. Commun. (1999), p. 2323.

Research paper thumbnail of Porphyrin Nanorods Modified Glassy Carbon Electrode for the Electrocatalysis of Dioxygen, Methanol and Hydrazine

Electroanalysis, 2011

Porphyrin nanorods (PNR) were prepared by ionic self-assembly of two oppositely charged porphyrin... more Porphyrin nanorods (PNR) were prepared by ionic self-assembly of two oppositely charged porphyrin molecules consisting of free base meso-tetraphenylsulfonate porphyrin (H 4 TPPS 4 2À) and meso-tetra(N-methyl-4-pyridyl) porphyrin (MTMePyP 4 + M = Sn, Mn, In, Co). These consist of H 4 TPPS 4

Research paper thumbnail of Effect of Heat on the Morphology and Optical Properties of Porphyrin Nanostructures

Synthesis and Reactivity in Inorganic Metal-organic and Nano-metal Chemistry - SYNTH REACT INORG MET-ORG NAN, 2008

Porphyrin nanostructures of well-defined shapes were prepared by ionic self-assembly of two oppos... more Porphyrin nanostructures of well-defined shapes were prepared by ionic self-assembly of two oppositely charged porphyrins. These nanostructures were prepared using meso-tetra(4-phenylsulfonic acid) porphyrin, tin (IV) meso-tetra(4-pyridyl)porphyrin dichloride and vanadium (IV) oxide meso-tetra (4-pyridyl)porphyrin. The effect of heat resulted in intense agglomeration and production of porphyrin nanotubes of larger sizes and a greater population. These features of nanoporphyrins structures were observed using transmission electron microscope (TEM) and scanning electron microscope (SEM). UV-VIS absorption spectra of the samples show that those prepared at 70°C have intense soret bands, with broadening of J-aggregate bands, when compared with those prepared at room temperature.

Research paper thumbnail of Time dependency for the fabrication of porphyrin nanorods via ionic self-assembly: H4TPPS42- – SnTPy4+

Meso-tetra(4-phenylsulfonic acid)porphyrin (H 4 TPPS 4 2-) and tin(IV) meso-tetra(4-pyridyl)porph... more Meso-tetra(4-phenylsulfonic acid)porphyrin (H 4 TPPS 4 2-) and tin(IV) meso-tetra(4-pyridyl)porphyrin dichloride (SnTPyP 2+ ) porphyrin nanorods were prepared at room temperature by ionic self-assembly of these two oppositely charged porphyrins. The UV-VIS absorption spectra of the samples were measured hourly for the first six hours (after mixing the two porphyrin compounds) and then on a 24 hourly basis for 96 hour period. The spectra show a decrease in absorbance accompanied by a broadening of the absorption bands especially the J-aggregate bands with a red shift. This phenomenon was more pronounced after 24 hours, and no significant decrease in absorbance was observed after 72 hours. Transmission Electron Microscope (TEM) images of the product confirm the formation of the nanorods.

Research paper thumbnail of Absorbance and Flourescence Studies on Porphyrin Nanostructure (PNR) as a Light Harvester in Dye Sensitized Solar Cells

Porphyrin nanorods (PNR) were fabricated by electrostatic self-assembly of two oppositely charge ... more Porphyrin nanorods (PNR) were fabricated by electrostatic self-assembly of two oppositely charge molecules 4and the compounds used were free base meso-tetra-(4-sulphonatephenyl) porphyrin (H TPPS ) and metallo 2 4 4+ meso-tetra (4-N-methylpyridyl) porphyrin (MTMPyP ) (M = Sn, Mn, Co, In). The aim of this work was to study some photophysical properties of PNR for application as light harvester in dye sensitized solar cells. These properties included absorbance, fluorescence, and fluorescence quantum yield and lifetime. The results of Transmission Electron Microscope (TEM) images showed the formation of nanorods. Electronic Spectra of the PNR revealed J-aggregation bands at 492 nm and accompanied by a band at 712 nm. All the porphyrin nanostructures produced fluorescence at 670 nm when excited at 430 nm and each spectrum had a hidden band at 730 nm. The fluorescence quantum yields were low but deconvolution of the bi-exponential decay curves showed the existence of two species with lifetimes of ~3 ns and ~200 ps.

Research paper thumbnail of Porphyrin-Phthalocyanine Nanorods (P-PcNR) formed by Electrostatic Self-Assembly

Porphyrin-Phthalocyanine nanorods had been formed by electrostatic self-assembly of two oppositel... more Porphyrin-Phthalocyanine nanorods had been formed by electrostatic self-assembly of two oppositely charged 4complexes. The negatively charged complex was meso-tetra-4-phenylsulfonated porphyrin (H TPPS ) and the two 2 4 positively charged complex were tin and indium complexes of tetra {2,(3)-(2-mercaptopyridine) phthalocyaninato}(MTSPyPc). The transmission electron microscope (TEM) images of the colloid suspension of the aggregate confirmed formation of nanorods while their electron spectra showed that the molecules formed J-aggregation.

Research paper thumbnail of Electrostatic self-assembly of quaternized 2,(3)-tetra(oxo-pyridine) phthalocyaninato chloroindium(III) with a series of tetrasulfonated phthalocyanines

Polyhedron, 2009

The self-assembly of oppositely charged phthalocyanines, fabricated using quaternized 2,(3)-tetra... more The self-assembly of oppositely charged phthalocyanines, fabricated using quaternized 2,(3)-tetra(oxopyridine) phthalocyaninato chloroindium (III) (QInPyPc) as the positively charge molecule and a series of tetrasulfonate phthalocyanine (MTSPc), M = 2H, Mn, Fe, Co and Ni as negatively charged molecules are reported. The self-assembly results in the formation of heteroaggregates. The metallated sulfonated phthalocyanines form nanorod and nanoleaf shaped structures as evidenced by transmission electron microscopy (TEM). The UV-Vis spectra showed blue shifted Q bands, suggesting that these structures were in a face-to-face arrangement. The Raman spectra of the heteroaggregates showed shifting compared to the spectra of the precursors.

Research paper thumbnail of Spectroscopic studies of nanostructures of negatively charged free base porphyrin and positively charged tin porphyrins

Polyhedron, 2010

... Medicinal Chemistry and Nanotechnology and Rhodes University. Reama George thanks Third World... more ... Medicinal Chemistry and Nanotechnology and Rhodes University. Reama George thanks Third World Organization of Women in Science (TWOWS) for a bursary. References. [1] HL Anderson, Chem. Commun. (1999), p. 2323.

Research paper thumbnail of A DFT/TD-DFT study on the possible replacement of Ru(II) with Fe(II) in phthalocyanine-based dye-sensitized solar cells

Research paper thumbnail of Characterization of porphyrin nanorods on fluorine doped tin oxide glass sheet

Journal of Porphyrins and Phthalocyanines, 2015

Porphyrin nanorods (PNR) have been fabricated by electrostatic self-assembly of two oppositely ch... more Porphyrin nanorods (PNR) have been fabricated by electrostatic self-assembly of two oppositely charged porphyrin molecules. The free base meso-tetra-(4-phenylsulphonate) porphyrin (TPPS[Formula: see text] served as negatively charged counterpart for the positively charged metallo meso-tetra(4-[Formula: see text]-methylpyridyl) porphyrins (MTM’PyP) with either Sn, Co, Mn or In as central metal M. Films of PNR were prepared on fluorine doped tin oxide glass sheets (FTO) by using a drop-dry method. The electronic spectra revealed J-aggregation of the charged molecules for the colloid PNR as well as for the films. Transmission electron microscopy confirmed the formation of porphyrin nanorods. The laser microscope and scanning electron microscope (SEM) images of the PNR/FTO films showed the formation of three kinds of structures in the films which consist of differently branched or linear needles with their main axis grown in the direction of the solvent flow during preparation. During c...

Research paper thumbnail of Enhanced triplet state yields in aqueous media of asymmetric zinc phthalocyanines when conjugated to silver nanoflowers

Research paper thumbnail of Phytoremediation of Lindane and Dieldrin: A Screening Study

Research paper thumbnail of Absorbance and Fluorescence Studies on Porphyrin Nanostructures (PNR) as Light Harvesters in Dye Sensitized Solar Cells

Porphyrin nanorods (PNR) were fabricated by electrostatic self-assembly of two oppositely charge ... more Porphyrin nanorods (PNR) were fabricated by electrostatic self-assembly of two oppositely charge molecules and the compounds used were free base meso-tetra-(4-sulphonatephenyl) porphyrin (H2TPPS44-) and metallo meso-tetra (4-N-methylpyridyl) porphyrin (MTMPyP4+) (M = Sn, Mn, Co, In). The aim of this work was to study some photophysical properties of PNR for application as light harvester in dye sensitized solar cells. These properties include absorbance, fluorescence, and fluorescence quantum yield and lifetime. The results of Transmission Electron Microscope (TEM) images showed the formation of nanorods. Electronic Spectra of the PNR revealed J-aggregation bands at 492 nm and accompanied by a band at 712 nm. All the porphyrin nanostructures produced fluorescence at 670 nm when excited at 430 nm and each spectrum had a hidden band at 730 nm. The fluorescence quantum yields were low but deconvolution of the bi-exponential decay curves showed the existence of two species with lifetime...

Research paper thumbnail of Spectroscopic studies of nanostructures of negatively charged free base porphyrin and positively charged tin porphyrins

Polyhedron, 2010

... Medicinal Chemistry and Nanotechnology and Rhodes University. Reama George thanks Third World... more ... Medicinal Chemistry and Nanotechnology and Rhodes University. Reama George thanks Third World Organization of Women in Science (TWOWS) for a bursary. References. [1] HL Anderson, Chem. Commun. (1999), p. 2323.

Research paper thumbnail of Porphyrin Nanorods Modified Glassy Carbon Electrode for the Electrocatalysis of Dioxygen, Methanol and Hydrazine

Electroanalysis, 2011

Porphyrin nanorods (PNR) were prepared by ionic self-assembly of two oppositely charged porphyrin... more Porphyrin nanorods (PNR) were prepared by ionic self-assembly of two oppositely charged porphyrin molecules consisting of free base meso-tetraphenylsulfonate porphyrin (H 4 TPPS 4 2À) and meso-tetra(N-methyl-4-pyridyl) porphyrin (MTMePyP 4 + M = Sn, Mn, In, Co). These consist of H 4 TPPS 4

Research paper thumbnail of Effect of Heat on the Morphology and Optical Properties of Porphyrin Nanostructures

Synthesis and Reactivity in Inorganic Metal-organic and Nano-metal Chemistry - SYNTH REACT INORG MET-ORG NAN, 2008

Porphyrin nanostructures of well-defined shapes were prepared by ionic self-assembly of two oppos... more Porphyrin nanostructures of well-defined shapes were prepared by ionic self-assembly of two oppositely charged porphyrins. These nanostructures were prepared using meso-tetra(4-phenylsulfonic acid) porphyrin, tin (IV) meso-tetra(4-pyridyl)porphyrin dichloride and vanadium (IV) oxide meso-tetra (4-pyridyl)porphyrin. The effect of heat resulted in intense agglomeration and production of porphyrin nanotubes of larger sizes and a greater population. These features of nanoporphyrins structures were observed using transmission electron microscope (TEM) and scanning electron microscope (SEM). UV-VIS absorption spectra of the samples show that those prepared at 70°C have intense soret bands, with broadening of J-aggregate bands, when compared with those prepared at room temperature.

Research paper thumbnail of Time dependency for the fabrication of porphyrin nanorods via ionic self-assembly: H4TPPS42- – SnTPy4+

Meso-tetra(4-phenylsulfonic acid)porphyrin (H 4 TPPS 4 2-) and tin(IV) meso-tetra(4-pyridyl)porph... more Meso-tetra(4-phenylsulfonic acid)porphyrin (H 4 TPPS 4 2-) and tin(IV) meso-tetra(4-pyridyl)porphyrin dichloride (SnTPyP 2+ ) porphyrin nanorods were prepared at room temperature by ionic self-assembly of these two oppositely charged porphyrins. The UV-VIS absorption spectra of the samples were measured hourly for the first six hours (after mixing the two porphyrin compounds) and then on a 24 hourly basis for 96 hour period. The spectra show a decrease in absorbance accompanied by a broadening of the absorption bands especially the J-aggregate bands with a red shift. This phenomenon was more pronounced after 24 hours, and no significant decrease in absorbance was observed after 72 hours. Transmission Electron Microscope (TEM) images of the product confirm the formation of the nanorods.

Research paper thumbnail of Absorbance and Flourescence Studies on Porphyrin Nanostructure (PNR) as a Light Harvester in Dye Sensitized Solar Cells

Porphyrin nanorods (PNR) were fabricated by electrostatic self-assembly of two oppositely charge ... more Porphyrin nanorods (PNR) were fabricated by electrostatic self-assembly of two oppositely charge molecules 4and the compounds used were free base meso-tetra-(4-sulphonatephenyl) porphyrin (H TPPS ) and metallo 2 4 4+ meso-tetra (4-N-methylpyridyl) porphyrin (MTMPyP ) (M = Sn, Mn, Co, In). The aim of this work was to study some photophysical properties of PNR for application as light harvester in dye sensitized solar cells. These properties included absorbance, fluorescence, and fluorescence quantum yield and lifetime. The results of Transmission Electron Microscope (TEM) images showed the formation of nanorods. Electronic Spectra of the PNR revealed J-aggregation bands at 492 nm and accompanied by a band at 712 nm. All the porphyrin nanostructures produced fluorescence at 670 nm when excited at 430 nm and each spectrum had a hidden band at 730 nm. The fluorescence quantum yields were low but deconvolution of the bi-exponential decay curves showed the existence of two species with lifetimes of ~3 ns and ~200 ps.

Research paper thumbnail of Porphyrin-Phthalocyanine Nanorods (P-PcNR) formed by Electrostatic Self-Assembly

Porphyrin-Phthalocyanine nanorods had been formed by electrostatic self-assembly of two oppositel... more Porphyrin-Phthalocyanine nanorods had been formed by electrostatic self-assembly of two oppositely charged 4complexes. The negatively charged complex was meso-tetra-4-phenylsulfonated porphyrin (H TPPS ) and the two 2 4 positively charged complex were tin and indium complexes of tetra {2,(3)-(2-mercaptopyridine) phthalocyaninato}(MTSPyPc). The transmission electron microscope (TEM) images of the colloid suspension of the aggregate confirmed formation of nanorods while their electron spectra showed that the molecules formed J-aggregation.

Research paper thumbnail of Electrostatic self-assembly of quaternized 2,(3)-tetra(oxo-pyridine) phthalocyaninato chloroindium(III) with a series of tetrasulfonated phthalocyanines

Polyhedron, 2009

The self-assembly of oppositely charged phthalocyanines, fabricated using quaternized 2,(3)-tetra... more The self-assembly of oppositely charged phthalocyanines, fabricated using quaternized 2,(3)-tetra(oxopyridine) phthalocyaninato chloroindium (III) (QInPyPc) as the positively charge molecule and a series of tetrasulfonate phthalocyanine (MTSPc), M = 2H, Mn, Fe, Co and Ni as negatively charged molecules are reported. The self-assembly results in the formation of heteroaggregates. The metallated sulfonated phthalocyanines form nanorod and nanoleaf shaped structures as evidenced by transmission electron microscopy (TEM). The UV-Vis spectra showed blue shifted Q bands, suggesting that these structures were in a face-to-face arrangement. The Raman spectra of the heteroaggregates showed shifting compared to the spectra of the precursors.

Research paper thumbnail of Spectroscopic studies of nanostructures of negatively charged free base porphyrin and positively charged tin porphyrins

Polyhedron, 2010

... Medicinal Chemistry and Nanotechnology and Rhodes University. Reama George thanks Third World... more ... Medicinal Chemistry and Nanotechnology and Rhodes University. Reama George thanks Third World Organization of Women in Science (TWOWS) for a bursary. References. [1] HL Anderson, Chem. Commun. (1999), p. 2323.