Papers by Nada Dimitrijevic
The Journal of Physical Chemistry Letters, 2013
Salicylate and salicylic acid derivatives act as electron donors via charge-transfer complexes wh... more Salicylate and salicylic acid derivatives act as electron donors via charge-transfer complexes when adsorbed on semiconducting surfaces. When photoexcited, charge is injected into the conduction band directly from their highest occupied molecular orbital (HOMO) without needing mediation by the lowest unoccupied molecular orbital (LUMO). In this study, we successfully induce the chemical participation of carbon dioxide in a charge transfer state using 3-aminosalicylic acid (3ASA). We determine the geometry of CO2 using a combination of ultraviolet-visible spectroscopy (UV-vis), surface enhanced Raman scattering (SERS), (13)C NMR, and electron paramagnetic resonance (EPR). We find CO2 binds on Ti sites in a carbonate form and discern via EPR a surface Ti-centered radical in the vicinity of CO2, suggesting successful charge transfer from the sensitizer to the neighboring site of CO2. This study opens the possibility of analyzing the structural and electronic properties of the anchoring sites for CO2 on semiconducting surfaces and proposes a set of tools and experiments to do so.
Journal of the American Chemical Society, 2009
Modification of TiO(2) nanoparticles with dopamine enables harvesting of visible light and promot... more Modification of TiO(2) nanoparticles with dopamine enables harvesting of visible light and promotes spatial separation of charges. The formation of reactive oxygen species (OH, (1)O(2), O(2)(-), HO(2), H(2)O(2)) upon illumination of TiO(2)/dopamine was studied using complementary spin-trap EPR and radical-induced fluorescence techniques. The localization of holes on dopamine suppresses oxidation of adsorbed water molecules at the surface of nanoparticles, and thus formation of OH radicals. At the same time, dopamine does not affect electronic properties of photogenerated electrons and their reaction with dissolved oxygen to produce superoxide anions. Superoxide anions are proposed to generate singlet oxygen through dismutation reaction, resulting in a low yield of (1)O(2) detected.
The Journal of Physical Chemistry, 1989
ABSTRACT
The Journal of Physical Chemistry, 1993
Excited-state properties and one-electron reduction of C60 in aqueous y-cyclodextrin (y-CD) solut... more Excited-state properties and one-electron reduction of C60 in aqueous y-cyclodextrin (y-CD) solutions have been studied by laser flash photolysis and pulse radiolysis techniques. The difference absorption spectrum of C~O -anion radical in aqueous y-CD solution has been characterized by reducing Cw with radiolytically produced radicals (eaq-, (CH&COH or MV'+). The one-electron reduction potential of the ground-state Cm in aqueous y-cyclodextrin solution (Eo = -0.25 V vs N H E ) has been measured by equilibrating fullerene solution with MV2+/MV*+ couple. Inorganic anions, such as N3-, I-, N01, ClOl and SCN-, quench the excited triplet c 6 0 and participate in the electron-transfer process.
The Journal of Physical Chemistry, 1989
Photoinduced blue shifts in CdS colloids have been time resolved by picosecond pump-probe measure... more Photoinduced blue shifts in CdS colloids have been time resolved by picosecond pump-probe measurements. The blue shift appears within the time domain of the pump pulse (18 ps) and is found to increase with increased pump light intensity. Calculations of the predicted blue shift from a dynamic Burstein-Moss shift agree with the experimental results at the lower laser intensities, but
The Journal of Physical Chemistry, 1987
The Journal of Physical Chemistry, 1993
ABSTRACT
The Journal of Physical Chemistry, 1992
45) Felton, R. H.; Yu, N.-T. In The Porphyrins; Dolphin, D., Ed.; Aca-(46) Spiro, T. G. In Iron P... more 45) Felton, R. H.; Yu, N.-T. In The Porphyrins; Dolphin, D., Ed.; Aca-(46) Spiro, T. G. In Iron Porphyrins; Lever, A. P. B., Gray, H. B., Eds.; (47) Gouterman, M. In The Porphyrins; Dolphin, D., Ed.; Academic: (48) Shelnutt, J. A.; Cheung, L. D.; Chang, R. C. C.; Yu, N.-T.; Felton, (49) Sekino, H.; Kobayashi, H.
Solar Energy, 1990
... history of colloid chemistry dates back to 1861 when the British chemist Thomas Graham referr... more ... history of colloid chemistry dates back to 1861 when the British chemist Thomas Graham referred to Address correspondence to Prashant V. Kamat ... Complexation of [Fe(CN)6]4 with colloidal TIO2188] and diethyldithiocarba mate anion with colloidal CDS[89] was found to mod ...
We report pronounced and specific antiglioblastoma cell phototoxicity of 5 nm TiO 2 particles cov... more We report pronounced and specific antiglioblastoma cell phototoxicity of 5 nm TiO 2 particles covalently tethered to an antibody via a dihydroxybenzene bivalent linker. The linker application enables absorption of a visible part of the solar spectrum by the nanobio hybrid. The phototoxicity is mediated by reactive oxygen species (ROS) that initiate programmed death of the cancer cell. Synchrotron X-ray fluorescence microscopy (XFM) was applied for direct visualization of the nanobioconjugate distribution through a single brain cancer cell at the submicrometer scale.
The Journal of Physical Chemistry B, 2003
Excess electrons in nanocrystalline TiO 2 were studied in bare and dopamine-capped TiO 2 nanopart... more Excess electrons in nanocrystalline TiO 2 were studied in bare and dopamine-capped TiO 2 nanoparticles by electron-beam pulse radiolysis. Reaction of hydrated electrons with dopamine-capped TiO 2 nanoparticles was found to be at the diffusion-controlled limit, k ) 1 × 10 11 M -1 s -1 , while the reaction with 1-hydroxy-1methylethyl radicals, (CH 3 ) 2 Ċ OH, was 2 orders of magnitude slower, k ) 4 × 10 8 M -1 s -1 . The reactions result in injection of electrons into the conduction band of TiO 2 nanoparticles. Optical absorption spectra of injected excess electrons in dopamine-capped nanoparticles display monotonic featureless wavelength dependence up to 1800 nm. In contrast, bare particles have shown two preferential optical transitions with energies in the visible region (λ max ) 670 nm and λ max ) 900 nm). Flat band potential of dopamine-capped TiO 2 nanoparticles was shifted by 100 mV to more negative values. The strong coupling of dopamine to surface Ti atoms was also found to improve the separation of photogenerated charges. This was demonstrated by the enhanced efficiency of photogenerated electrons in reducing silver cations to metallic silver in systems linked via a dopamine bridge, compared to the same systems linked through carboxyl groups. † Part of the special issue "Arnim Henglein Festschrift". 10.
International journal of nanoscience, Aug 1, 2011
Functional nanoscale materials that possess specific physical or chemical properties can leverage... more Functional nanoscale materials that possess specific physical or chemical properties can leverage energy transduction in vivo. Once these materials integrate with biomolecules they combine physical properties of inorganic material and the biorecognition capabilities of bio-organic moieties. Such nano-bio hybrids can be interfaced with living cells, the elementary functional units of life. These nano-bio systems are capable of bio-manipulation or actuation via altering intracellular biochemical pathways. Thus, nano-bio conjugates are appealing for a wide range of applications from the life sciences and nanomedicine to catalysis and clean energy production. Here we highlight recent progress in our efforts to develop smart nano-bio hybrid materials, and to study their performance within cellular machinery under application of external stimuli, such as light or magnetic fields.
1997 21st International Conference on Microelectronics. Proceedings, 1997
A simple synthetic procedure for preparation of nanometer sized composite CdS/SiO2 particles with... more A simple synthetic procedure for preparation of nanometer sized composite CdS/SiO2 particles with core-shell structure was developed as well as route for isolation of solid materials based on the destabilization of colloidal solutions with adjustment of the pH at the value corresponding to the zero point charge of silica. The optical properties of isolated solid materials were identical to the optical properties of the precursor colloidal solutions. Also, the electron transfer through oxide layer was demonstrated in photochemical experiments by using methylviologen (1,1'-dimethyl-4,4'-bipyridinium-dichloride) as a test molecule
Materials Science Forum, 1998
Materials Science Forum, 1998
ACS nano, Jan 26, 2014
Photocatalytic production of clean hydrogen fuels using water and sunlight has attracted remarkab... more Photocatalytic production of clean hydrogen fuels using water and sunlight has attracted remarkable attention due to the increasing global energy demand. Natural and synthetic dyes can be utilized to sensitize semiconductors for solar energy transformation using visible light. In this study, reduced graphene oxide (rGO) and a membrane protein bacteriorhodopsin (bR) were employed as building modules to harness visible light by a Pt/TiO2 nanocatalyst. Introduction of the rGO boosts the nano-bio catalyst performance that results in hydrogen production rates of approximately 11.24 mmol of H2 (μmol protein)(-1) h(-1). Photoelectrochemical measurements show a 9-fold increase in photocurrent density when TiO2 electrodes were modified with rGO and bR. Electron paramagnetic resonance and transient absorption spectroscopy demonstrate an interfacial charge transfer from the photoexcited rGO to the semiconductor under visible light.
Journal of Physical Chemistry B, 1999
Aqueous suspensions of silica particles at high concentrations were irradiated with a short pulse... more Aqueous suspensions of silica particles at high concentrations were irradiated with a short pulse of electrons in the presence of scavengers of OH radicals. The scavengers were chosen to minimize their adsorption on the particle surface. It was found that essentially no holes cross the particle/water interface to generate OH radicals. All of the holes that are originally generated by
International Journal of Modern Physics B, 2009
ABSTRACT Rational design of hybrid biomolecule --- nanoparticulate semiconductor conjugates enabl... more ABSTRACT Rational design of hybrid biomolecule --- nanoparticulate semiconductor conjugates enables coupling of functionality of biomolecules with the capability of semiconductors for solar energy capture, that can have potential application in energy conversion, sensing and catalysis. The particular challenge is to obtain efficient charge separation analogous to the natural photosynthesis process. The synthesis of axially anisotropic TiO2 nano-objects such as tubes, rods and bricks, as well as spherical and faceted nanoparticles has been developed in our laboratory. Depending on their size and shape, these nanostructures exhibit different domains of crystallinity, surface areas and aspect ratios. Moreover, in order to accommodate for high curvature in nanoscale regime, the surfaces of TiO2 nano-objects reconstructs resulting in changes in the coordination of surface Ti atoms from octahedral (D2d) to square pyramidal structures (C4v). The formation of these coordinatively unsaturated Ti atoms, thus depends strongly on the size and shape of nanocrystallites and affects trapping and reactivity of photogenerated charges. We have exploited these coordinatively unsaturated Ti atoms to coupe electron-donating (such as dopamine) and electron-accepting (pyrroloquinoline quinone) conductive linkers that allow wiring of biomolecules and proteins resulting in enhanced charge separation which increases the yield of ensuing chemical transformations.
ChemInform, 2001
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Materials Syntheses, 2008
... ceived. Argon gas, high purity 99,998 purchased from AGA Gas. Safety and Disposal ... 175. ... more ... ceived. Argon gas, high purity 99,998 purchased from AGA Gas. Safety and Disposal ... 175. [2] RP Andres, T. Bein, M. Dorogi, S. Feng, JI Henderson, CB Kubiak, W. Mahoney, R. G. Osifchin, R. Reifenberger, Science 1996, 272, 1323. ...
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Papers by Nada Dimitrijevic