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Background: The aim of the work was a prospective study of utilization review for multiple antibiotics prescribed in the specialty department in a tertiary care teaching hospital.Methods: A prospective study was conducted for 6 months in specialty department in a tertiary care teaching hospital.Results: In the 6 months duration of the study, a total number of 96 prescriptions were analyzed. The 77 prescriptions were prescribed with Beta-lactam antibiotics. and remaining prescriptions were prescribed with 2, 3 and 4-5 different classes of antibiotics.Conclusions: The result obtained from our study is for judgment use of antibiotics will reduce the burden of multi-drug resistance and thereby enable better patient management and limit patient morbidity and mortality.

Here, CO gas environment has been used for reduction of graphene oxide (GO) and Pd precursor for preparation of varieties of Pd Nanostructures (PdNSs) with different shapes, size and surface morphologies on graphene support (RG-PdNSs). The extensive ab-initio Molecular Dynamics (MD) simulations and electronic structure calculations have been carried to get theoretical insight for the reduction process of GO by CO. The reduction of GO by CO as observed in experiment are confirmed by ab-initio MD snapshots at different time steps, energetic of the process and the Partial Density of States character of O2p orbital of GO before and after interaction with CO. The discrete states in the Partial Density of States of O2p orbital after CO attack indicates detachment of O from GO. The as-prepared RG-PdNSs are thoroughly characterized by different techniques. The simulation reveals the change in electronic properties from semi-metallic in pristine graphene to metallic due to the attachment of Pd in RG-PdNSs. The electrocatalytic activity of the as-synthesized nanostructures has been investigated toward the multi-functional energy conversion applications, the methanol oxidation reaction, formic acid oxidation reaction and oxygen reduction reaction. The RG-PdNSs exhibit excellent electrocatalytic performance compared to that of unsupported PdNSs and commercial Pd/C.

We demonstrate how the morphology of a simple metal-oxide system (e.g., Cu2O) controls catalytic activity. Cu2O catalysts were synthesized with a highly uniform nanocube and nano-octahedra morphology under PVP surfactant-assisted reaction conditions. A series of structural, morphological, optical and electrical characterizations are done to optimize the growth of nanostructures with different morphologies. Finally, the nanostructures are exploited as photo- and electrocatalysts. Interestingly, we find dissimilitude behaviour of nano-octahedra and nano-cube samples towards photo and electrocatalytic activities. The nano-octahedra samples are ∼57% more photocatalytically active (half-life timeoctahedra ∼ 10.7 minutes) than the nanocube samples, which is one of the highest reported photocatalytic efficiencies reported to date. However, the same nano-octahedra samples show lower electrocatalytic activity towards oxygen reduction reaction (ORR) as compared with the nanocube sample.

We present doubly-resonant sum frequency generation (DR-SFG) spectra of fullerene thin films on metallic and dielectric substrates as a way to investigate the interplay between nuclear and electronic coupling at buried interfaces. Modal and substrate selectivity in the electronic enhancement of the C60 vibrational signatures is demonstrated for excitation wavelengths spanning the visible range. While the SFG response of the totally symmetric Ag(2) mode of fullerene is distinctly coupled to the optically allowed electronic transition corresponding to the HOMO–LUMO+1 of C60 (ca. 2.6 eV), the T1u(4) vibrational mode appears to be coupled to a symmetry-forbidden HOMO–LUMO transition at lower energies (ca. 2.0 eV). For dielectric substrates, the DR-SFG intensity of the T1u(4) mode shows lack of enhancement for upconversion wavelengths off-resonance with the optically-dark LUMO. However, the T1u(4) mode shows a unique coupling to an intermediate state (∼2.4 eV) only for the fullerene films on the gold substrate. We attribute this coupling to unique interactions at the buried C60/gold interface. These results demonstrate the occurrence of clear electron–phonon couplings at the C60/substrate interfaces and shed light on the impact of these couplings on the optical response of electronically excited fullerene. This coupling may influence charge and energy transport in organic electronic devices mediated by vibrational motions. We also demonstrate a potential use of this added selectivity in chemical imaging.

Heavy metal ions are a naturally occurring element that is toxic. The overuse of these heavy metal-based compounds in industry, agriculture, domestic, and technological practices leads to exposure in the environment that may have adverse effects on human health and the ecology. Considering their toxicity, the detection of metal ions is crucial, and many analytical methods are used to monitor them. Electrochemical methods have attracted considerable attention due to good sensitivity, low detection limit, and short analysis time and portability. To increase the sensitivity and selectivity of detection, research has focused on developing high surface area nanostructured electrode materials including inorganic, organic, polymer, and corresponding hybrid-based composites. The properties of graphene, a family of 2D layered material, has ignited the scientific community to discover other layered materials and explore their electrochemical sensing application toward toxic metal ions. This chapter provides an overview of materials developed for detection of heavy metal ions contaminants, particularly the graphene and functionalized graphene-based nanomaterials.

The exceptional properties of graphene-based derivatives have governed numerous research fields in recent years. The scaled up and reliable production of high-quality graphene is still a challenging task. This work presents an efficient and low-cost approach for the mass production of high-quality graphene (50 g scale batch) through the dual-drive planetary ball milling of graphite with a dicarboxylic acid. The dimensional changes of graphite were determined from the diffraction pattern of the (002) plane at different milling times and the unique signature of graphene noticed in the Raman spectra. Transmission electron microscopy clearly revealed the existence of single and bilayer graphene sheets. Non-destructive exfoliation was evidenced by the surface binding states of the C 1s core level spectra. The as-synthesized graphene was utilized as the catalytic support for formic acid fuel cell applications. Graphene supported palladium nanocomposites were prepared, and the electrocatalytic activity towards formic acid oxidation was explored. The cyclic voltammogram of the graphene–palladium nanocomposite reveals that the onset potential for formic acid oxidation is −0.1 V with a prominent oxidation peak at 0.263 V.

This work demonstrates the synthesis, characterization and electrochemical application of hollow-like Mn3O4 nanostructures well-dispersed on graphene matrix (MnH/G). The as-synthesized MnH/G shows favorable electrochemical properties for energy conversion application towards oxygen reduction reaction (ORR) and energy storage towards supercapacitor. The MnH/G efficiently catalyzes the ORR at lower potential and possesses the methanol tolerance activity that may find promising application as an alternative to Pt/C, which is susceptible to tolerance towards methanol crossover. Also, MnH/G exhibits the supercapacitance properties with 97% of capacitance retention over 2000 cycles. The MnH/G shows the practical usefulness by fabricating the coin-cell type supercapacitor towards powering the light-emitting diode (LED) light. Further, the density functional theory (DFT) simulations investigate the geometry and electronic properties of Mn3O4, and with graphene matrix. The theoretical calculation computes the overpotential for ORR activities of the hybrid structures from the adsorption energy of O, OH, and OOH species. The experimentally obtained overpotential is in good agreement with the theoretically calculated overpotential. The enhanced quantum capacitance for the hybrid structures obtained from DFT simulations supports experimental findings. The present report demonstrates a new and reasonable design of preparing non-precious nanomaterials with complex structures towards the methanol tolerance ORR and supercapacitor applications.

A new single layer graphene oxide hybrid polymeric material was fabricated in which the fullerene moieties covalently attached to the edges of surface of SLGO sheets were coordinated to palladium atom in an η2-fasion, SLGO-php-C60/Pd. The polymer was characterized by SEM, TEM, FT-IR and Raman techniques. The newly formed material exhibited reversible electrochemical activity in the negative potential range due to the reduction of fullerene cages with an overall electrochemical behavior resembling that of typical organic conducting polymers. The electron density of states calculated using DFT method clearly confirmed the fullerene cage reduction via electron transfer from the low-lying SLGO states. Therefore, coordination polymers of fullerene moieties bonded to the graphene sheets are easier to reduce in comparison to the coordination polymers of pristine C60. In addition, the spectroscopic and electrochemical properties of SLGO-php-C60/Pd hybrid polymeric material were also compared with php-C60/Pd polymer and SLGO-php-C60 hybrid films to seek film morphology-property relations. The present study extends the application of graphene oxide providing electrically conducting, redox-active polymer material for different applications.

High oxidation potential perfluorinated zinc phthalocyanines (ZnF(n)Pcs) are synthesised and their spectroscopic, redox, and light-induced electron-transfer properties investigated systematically by forming donor-acceptor dyads through metal-ligand axial coordination of fullerene (C60) derivatives. Absorption and fluorescence spectral studies reveal efficient binding of the pyridine- (Py) and phenylimidazole-functionalised fullerene (C60Im) derivatives to the zinc centre of the F(n)Pcs. The determined binding constants, K, in o-dichlorobenzene for the 1:1 complexes are in the order of 10(4) to 10(5) M(-1); nearly an order of magnitude higher than that observed for the dyad formed from zinc phthalocyanine (ZnPc) lacking fluorine substituents. The geometry and electronic structure of the dyads are determined by using the B3LYP/6-31G* method. The HOMO and LUMO levels are located on the Pc and C60 entities, respectively; this suggests the formation of ZnF(n)Pc(.+)-C60Im(.-) and ZnF(n)Pc(.+)-C60Py(.-) (n=0, 8 or 16) intra-supramolecular charge-separated states during electron transfer. Electrochemical studies on the ZnPc-C60 dyads enable accurate determination of their oxidation and reduction potentials and the energy of the charge-separated states. The energy of the charge-separated state for dyads composed of ZnF(n)Pc is higher than that of normal ZnPc-C60 dyads and reveals their significance in harvesting higher amounts of light energy. Evidence for charge separation in the dyads is secured from femtosecond transient absorption studies in nonpolar toluene. Kinetic evaluation of the cation and anion radical ion peaks reveals ultrafast charge separation and charge recombination in dyads composed of perfluorinated phthalocyanine and fullerene; this implies their significance in solar-energy harvesting and optoelectronic device building applications.

The ability of high oxidation potential zinc porphyrins acting as electron donors in photoinduced electron-transfer reactions is investigated. Donor–acceptor dyads were assembled via metal–ligand axial coordination of either pyridine or phenylimidazole functionalized fulleropyrrolidine with zinc porphyrin functionalized with different numbers of halogen substituents on the meso-aryl rings. Optical absorption studies on complex formation revealed relatively higher binding constants. Efficient quenching of fluorescence was observed for the newly assembled dyads, revealing their ability to undergo photoinduced events. Differential pulse voltammetry studies were performed to understand the structure–activity relationships with respect to the electron deficient nature of the porphyrins and to utilize these data to estimate free-energy change for charge-separation and charge-recombination processes. The absolute value of free-energy change for charge separation was found to be lower for halogenated porphyrins w...

Photoexcited electron injection and back electron transfer dynamics of metal tetrapyrrole bound to TiO2 nanoparticle surfaces via the metal–ligand axial coordination approach have been investigated using femtosecond pump–probe transient spectroscopic technique. The employed metal tetrapyrroles include zinc and magnesium metalated meso-tetraarylporphyrins having halogen substituents on the peripheral aryl groups, perfluorinated zinc phthalocyanine derivatives, and zinc naphthalocyanine. The employed metal tetrapyrroles covered absorption at different portions of the visible and near-IR region of the spectrum with excited-state reduction potentials ranging between −0.61 eV and −1.34 V, that is, having energy higher than the TiO2 conduction band edge (−0.57 V vs NHE). Two linkers, pyridine and phenylimidazole, have been employed to visualize electronic coupling between the dye and metal oxide surface for optimal electron injection and back electron transfer dynamics. In agreement with the previously reported...

Photocatalytic behavior of a recently synthesized, single layer graphene oxide (SLGO) decorated with an electron donor, zinc phthalocyanine (ZnPc) and an electron acceptor, fulleropyrrolidine (C60) donor-acceptor hybrid is demonstrated. Electron accumulation in the form of one-electron reduced product of methyl viologen was obtained in high yields in an electron pooling experiment involving the ZnPc-SLGO-C60 hybrid and a sacrificial electron donor compared with control hybrids involving either ZnPc-SLGO or SLGO-C60 hybrids. This novel property of ZnPc-SLGO-C60 hybrid has been ascribed to the proximity effect offered by GO with covalently linked donor and acceptor entities on its surface. The present studies reveal that the ZnPc-SLGO-C60 hybrid is a suitable catalyst for solar fuel production.

A (carbon nanotube)–(fullerene–ferrocene dyad polymer) composite, pyr-SWCNTs/(C60Fc-Pd), was devised and tested as an active material of a symmetrical device for electric energy storage. The composite was redox conducting at both positive and negative potentials due to the Fc/Fc+ and C60–/C60 electrode process of the ferrocene and fullerene moiety of the dyad, respectively. The composite was prepared, first, by electrophoretic deposition of a film of noncovalently modified with 1-pyrenebutyric acid stacked single-wall carbon nanotubes (pyr-SWCNTs). Then, this film was coated, by potentiodynamic electropolymerization, with a film of the palladium-doped polymer of 2′-ferrocenylfulleropyrrolidine (C60Fc-Pd). The AFM imaging showed that the C60Fc-Pd film was uniformly built of 40–150 nm diameter globules of C60Fc-Pd while the film formed a tangle of pyr-SWCNTs bundles wrapped with clusters of ∼45 nm diameter globules of C60Fc-Pd. The XPS measurements identified interactions between the Pd and C60 moieties in ...

The molecular self-assembly of surfactants on the surface of single-walled carbon nanotubes (SWCNT) is currently a common strategy for the tuning of nanotube properties and the stabilization of carbon nanotube dispersions. Here, we report direct measurements of the degree of interfacial ordering for sodium dodecyl sulfate (SDS) surfactants adsorbed on colloidal, single-chirality enriched, SWCNTs within a solid film and investigate the dependence of surface alkyl chain order on the surfactant concentration in the precursor solution. The degree of order for the SWCNT-bound SDS molecules, is probed by vibrational sum frequency generation (VSFG) spectroscopy. We find concrete evidence for the presence of highly ordered surface structures at sufficiently high SDS concentrations, attributed here to cylindrical-like micelle assemblies with the SWCNT at the core. As the SDS concentration decreases, the interfacial order is found to decrease as well, generating a more disordered or random adsorption of surfactants on the nanotube surfaces.

Photoinduced electron transfer processes in self-assembled zinc porphyrin ( ZnP ) or zinc phthalocyanine ( ZnPc ) with semiconducting (7,6)- and (6,5)-enriched SWCNTs were investigated. To bind photosensitizers to SWCNTs, first, pyrene covalently functionalized with a phenylimidazole (Im-Pyr) entity was treated with SWCNTs. Exfoliation of SWCNTs occurred due to π–π stacking of pyrene with nanotubes walls leaving the imidazole entity that was subsequently used to coordinate ZnP or ZnPc in o-dichlorobenzene (DCB). The donor-acceptor nanohybrids thus formed were characterized by TEM imaging, steady-state UV-visible-near IR absorption and fluorescence spectra. Free-energy calculations suggested possibility of electron transfer from the photoexcited ZnP or ZnPc to Im-Pyr/SWCNT(n,m) in the nanohybrids. Consequently, steady-state and time-resolved fluorescence studies revealed efficient quenching of the singlet excited state of ZnP or ZnPc with the rate constants of charge separation (k CS ) in the range of (3–6) × 109 s-1. Nanosecond transient absorption technique confirmed the electron transfer products, ZnP·+←Im-Pyr/SWCNT·- and ZnPc·+←Im-Pyr/SWCNT·- (and opposite charged pairs) having characteristic absorptions with the decay rate constants due to charge recombination (k CR ) in the range of (1.4–2.4) × 107 s-1, corresponding to lifetimes of radical ion-pairs in the 70–100 ns range. The SWCNT·- was further utilized to mediate electrons to hexyl-viologen dication (HV2+) resulting in an electron-accumulation process in the presence of sacrificial electron donor, offering additional proof for the occurrence of photoinduced charge-separation and potential utilization of these materials in light energy harvesting applications. Further, photoelectrochemical cells have been constructed on FTO/ SnO2 electrodes to verify their ability to directly convert light into electricity. An IPCE efficiency of up to 7% has been achieved in case of ZnP←Im-Pyr/SWCNT modified electrode.

Photoinduced electron transfer in self-assembled via ion-pairing porphyrin–SWCNT nanohybrids has been reported. To accomplish this, two kinds of semiconducting SWCNTs of different diameters, and free-base or zinc porphyrin bearing peripheral positive or negative charges serving as light absorbing photo-active materials are utilized. The donor–acceptor hybrids are held by ion-pairing with the help of oppositely charged pyrene derivatives adhered to the side walls of SWCNTs. Higher charge-separation efficiency is established for thick SWCNT(7,6) with narrower band gap compared with the thin SWCNT(6,5) with wider band gap. Photoelectrochemical studies using FTO/SnO2 electrodes modified with these donor–acceptor nanohybrids unanimously demonstrated the ability of these nanohybrids to harvest light energy into electricity. Importantly, the photocurrent generation followed the trend observed for charge-separation, that is, incident-photon-to-current conversion efficiency of a maximum of 8% is achieved for photocells with SWCNT(7,6), while such conversion efficiencies are smaller for the cells derived from SWCNT(6,5). These results indicate that higher light energy conversion efficiencies are possible to achieve by the selection of the appropriate SWCNTs with right band gap on combination of appropriate porphyrins.

The superoxide anion radical, O2•−, induced C60 electropolymerization mechanism was refined by simultaneous cyclic voltammetric (CV) and vis-NIR spectroelectrochemical as well as mass spectrometric (MALDI-TOF) characterization of the one- and two-electron reduction products of C60 in the presence of O2 in a mixed organic solvent solution. The C60 polymer (C60-O) film was also investigated by Raman spectroscopy and imaged by atomic force microscopy (AFM) both at the early and advanced polymerization stage. While the spectroelectrochemical behavior of the C60/C60•− couple in the presence of O2 was similar to that in its absence, at more negative potentials corresponding to C602− and O2•− formation C602− participated in a chemical follow-up reaction resulting in a product lacking any diagnostic absorption band in the vis-NIR range. Although the main peak in the MS spectrum of the one-electron reduction product was that of C60 at m/z of 720, several additional peaks in the m/z range of 739−760 appeared, indic...

Donor–acceptor dyads featuring near-IR sensitizers derived from thieno-pyrrole-fused BODIPY (abbreviated as SBDPiR) and fullerene, C60 have been newly synthesized and characterized. Occurrence of ultrafast photoinduced electron transfer (PET) leading to the formation of charge-separated state in these dyads, capable of harvesting light energy from the near-IR region, is established from femtosecond transient absorption studies.

This paper investigates the synthesis of Ag NCs in Si(100) substrate by implanting multiple energies and fluences of Ag ions and subsequent thermal annealing.

We report the synthesis, photophysical and electrochemical properties, and in vivo fluorescence imaging of a series of new thieno–pyrrole-fused near-infrared (NIR) BODIPY agents by using a versatile intermediate as a building block. The versatile thieno– pyrrole-fused BODIPY intermediate was rationally designed to bear bromosubstituents and absorb in the mid-red region (635 nm) to act as an organic electrophile for the development of NIR multifunctional agents. The use of subsequent palladium-catalyzed and nucleophilic substitution reactions af forded highly conjugated NIR BODIPYs. The novel BODIPYs exhibit long-wavelength absorptions in the NIR region (650–840 nm). The agents produce sharp fluorescence bands, and most of them display respectable quantum yields of fluorescence (0.05–0.87) useful for biomedical imaging, as demonstrated by in vivo imaging with SBDPiR740. Interestingly, a number of agents in the series that are non-halogenated were reactive to O(2) at the triplet photo-excited state coupled with a favorable redox potential and decent fluorescence, and hence could be potential candidates for use as photosensitizers in fluorescence-guided photodynamic therapy. Furthermore, the synthetic approach allows further functionalization of the highly conjugated NIR BODIPYs to tune the excited states (PET, ICT) and to conjugate targeting moieties for enhanced biological applications.

Supramolecular donor-acceptor hybrids composed of few-layer graphene as an electron acceptor and phthalocyanine or porphyrin bearing four pyrene entities as photosensitizer donors have been synthesized, and occurrence of ultrafast charge separation in the order of 10(11)-10(12) s(-1) due to close proximity of the donor and acceptor entities is demonstrated.

Covalent functionalization of diameter sorted SWCNTs with porphyrins (MP), and photochemistry to establish nanotube diameter-dependent charge separation efficiencies are reported. The MP-SWCNT(n,m) [M=2H or Zn, and (n,m)=(7,6) or (6,5)] nanohybrids are characterized by a variety of spectroscopic, thermogravimetric, TEM imaging techniques, and also by DFT MO calculations. The thermogravimetric, Raman and fluorescence studies reveal the presence of a moderate number of porphyrins on the SWCNT surface. The MO results suggest charge separation (CS) via the excited state of MP. Time-resolved fluorescence studies reveal quenching of the singlet excited state of the MP with SWCNT(n,m), giving the rate constants of charge separation (k(CS)) in the range of (4-5)×10(9) s(-1). Nanosecond transient absorption measurements confirm the charge-separated radical cation and the radical anion as [MP(.+)-SWCNT(.-)] with their characteristic absorption bands in the visible and near-IR regions. The charge separated states persist for about 70-100 ns thus giving an opportunity to utilize them to build photoelectrochemical cells, which allowed us to derive the structure-reactivity relationship between the nature of porphyrin and diameter of the employed nanotubes.

Photoinduced charge separation processes of three-layer supramolecular hybrids, fullerene-porphyrin-SWCNT, which are constructed from semiconducting (7,6)- and (6,5)-enriched SWCNTs and self-assembled via π-π interacting long alkyl chain substituted porphyrins (tetrakis(4-dodecyloxyphenyl)porphyrins; abbreviated as MP(alkyl)(4)) (M = Zn and H(2)), to which imidazole functionalized fullerene[60] (C(60)Im) is coordinated, have been investigated in organic solvents. The intermolecular alkyl-π and π-π interactions between the MP(alkyl)(4) and SWCNTs, in addition, coordination between C(60)Im and Zn ion in the porphyrin cavity are visualized using DFT calculations at the B3LYP/3-21G(*) level, predicting donor-acceptor interactions between them in the ground and excited states. The donor-acceptor nanohybrids thus formed are characterized by TEM imaging, steady-state absorption and fluorescence spectra. The time-resolved fluorescence studies of MP(alkyl)(4) in two-layered nanohybrids (MP(alkyl)(4)/SWCNT) revealed efficient quenching of the singlet excited states of MP(alkyl)(4) ((1)MP*(alkyl)(4)) with the rate constants of charge separation (k(CS)) in the range of (1-9) × 10(9) s(-1). A nanosecond transient absorption technique confirmed the electron transfer products, MP˙(+)(alkyl)(4)/SWCNT˙(-) and/or MP˙(-)(alkyl)(4)/SWCNT˙(+) for the two-layer nanohybrids. Upon further coordination of C(60)Im to ZnP, acceleration of charge separation via(1)ZnP* in C(60)Im→ZnP(alkyl)(4)/SWCNT is observed to form C(60)˙(-)Im→ZnP˙(+)(alkyl)(4)/SWCNT and C(60)˙(-)Im→ZnP(alkyl)(4)/SWCNT˙(+) charge separated states as supported by the transient absorption spectra. These characteristic absorptions decay with rate constants due to charge recombination (k(CR)) in the range of (6-10) × 10(6) s(-1), corresponding to the lifetimes of the radical ion-pairs of 100-170 ns. The electron transfer in the nanohybrids has further been utilized for light-to-electricity conversion by the construction of proof-of-concept photoelectrochemical solar cells.

A non-covalent double-decker binding strategy is employed to construct functional supramolecular single-wall carbon nanotubes (SWCNT)-tetrapyrrole hybrids capable of undergoing photoinduced electron transfer and performing direct conversion of light into electricity. To accomplish this, two semiconducting SWCNTs of different diameters (6,5 and 7,6) were modified via π-π stacking of pyrene functionalized with an alkyl ammonium cation (PyrNH(3)(+)). Such modified nanotubes were subsequently assembled via dipole-cation binding of zinc porphyrin with one (1) or four benzo-18-crown-6 cavities (2) or phthalocyanine with four benzo-18-crown-6 cavities at the ring periphery (3), employed as visible-light photosensitizers. Upon charactering the conjugates using TEM and optical techniques, electron transfer via photoexcited zinc porphyrin and phthalocyanine was investigated using time-resolved emission and transient absorption techniques. Higher charge-separation efficiency is established for SWCNT(7,6) with a narrow band gap than the thin SWCNT(6,5) with a wide band gap. Photoelectrochemical studies using FTO/SnO(2) electrodes modified with these donor-acceptor conjugates unanimously demonstrated the ability of these conjugates to convert light energy into electricity. The photocurrent generation followed the trend observed for charge separation, that is, incident-photon-to-current efficiency (IPCE) of a maximum of 12 % is achieved for photocells with FTO/SnO(2)/SWCNT(7,6)/PyrNH(3)(+):1.

Supramolecular dyads of photosensitizing halogenated zinc porphyrins (and halogenated zinc phthalocyanines) and redox active fulleropyrolidine derivatives with pyridine or imidazole ligands were constructed based on metal-ligand axial coordination approach. Spectroscopic characterization accompanied by steady-state absorption and fluorescence studies confirmed the high binding affinity of the high potential zinc porphyrin towards fullerene ligands that was also supported by computational studies. Qualitative Benesi-Hildebrand plots allowed us to calculate the association constant, K of the supramolecular dyads. The redox states of the donor and acceptor entities in the dyads were established from electrochemical investigations using cyclic and differential pulse voltammetry techniques. Free energy calculations using Weller’s approach suggested exergonic photoinduced electron transfer process for all of the studied systems. Pump-probe transient absorption studies at the femtosecond and nanosecond time scale confirmed the formation of cation and anion radical ions in the donor-acceptor supramolecular dyads. The kinetics of charge separation and charge recombination evaluated from the transient absorption studies revealed occurrence of ultrafast electron transfer events.

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Graphene oxide decorated with an electron donor, zinc(II) phthalocyanine, and an electron acceptor, fullerene, has been synthesized, and photoinduced electron transfer leading to charge-separation is reported.

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A precise thermodynamic measurement of the equilibrium: C graphite = C glassy carbon employing a solid oxide electrolyte in the temperature range 650°–1150°C was carried out to gain structural information on glassy carbons. The measured Gibbs free energy change yields configurational (residual quantities at zero Kelvin) enthalpy and entropy differences, which represent a two parameter measure of the structural differences between a given glassy carbon and graphite, since the above reaction involves vanishingly small differences in composition, specific heat, and hence vibrational contributions. Many of the experimental and commercially available samples of glassy carbons studied exhibited at elevated temperature thermodynamic carbon activities lower than graphite. For various samples studied, the zero point entropy varied from 3.1 to 11.3cal/g-mole-°K. The thermodynamic parameters are correlated with X-ray and density measurements. The configurational enthalpy and entropy changes are interpreted in terms of strain related and atomic disorder parameters, respectively.

Dialkyl (3-aryl-l,2,4-oxadiazol-5-yl)phosphonate6sa -h have been obtained by 1,3-dipolar cycloaddition of arenenitrile oxides 5a-f to dialkyl phosphorocyanidates (4a and 4b) in yields ranging between 30% and 58%. A standardized method for obtaining cyanidates 4a and 4b has been established. The diethyl thiophosphorocyanidate (4c) is less reactive than 4a and 4b, only the 3-(4'-nitrophenyl) derivative 6i being obtainable. While the IR and NMFt spectra of 6a-i were unexceptional, their UV spectra showed evidence of conjugative interaction in high degrees between the phosphonate and heterocyclic moieties as well as a varying conjugative interaction between the heterocyclic and aryl moieties. The oxadiazoles 6a-h are thermally labile and yield trialkyl phosphates 7 as the only identifiable products. A mechanism based on the intermediacy of monomeric alkyl metaphosphate 11 in the formation of trialkyl phosphate was postulated, and supportive evidence in the form of trapping the metaphosphate with acetophenone has been obtained.

The reversible galvanic cell: Sn(l), SnO2(s)/CaO-ZrO2/Pb-Sn(l), SnO2(s) (electrolyte) was employed to determine the thermodynamic properties of liquid Pb-Sn alloys in the composition range ofXsn from 0.1 to 0.9 and in the temperature range of 875 to 1100 K. The activities of both tin and lead exhibit only moderate positive deviations from the respective Raoult’s law lines and do not agree with the values reported in the literature.SE, as calculated by combiningHE values of Kleppa andFE values determined in this investigation, are positive and range from 0 to 0.139 eu.

A calcia doped zirconia solid oxide electrolyte galvanic cell was investigated in the temperature range of 700–950°C to directly and more accurately measure the standard Gibbs free energy change of the following reactions: CO(g) + 1 2 O 2 (g) = CO 2 (g) C(graphite) + CO2(g) = 2 CO(g). The results obtained in the present investigation are well within the scatter band of the calorimetric and spectroscopic data.