Morteza Adinehnia

Bio: Morteza Adinehnia is an academic researcher from Washington State University. The author has contributed to research in topics: Porphyrin & Ionic bonding. The author has an hindex of 8, co-authored 13 publications receiving 211 citations. Previous affiliations of Morteza Adinehnia include Amirkabir University of Technology & Research Institute of Petroleum Industry.

Comprehensive structure–function correlation of photoactive ionic π-conjugated supermolecular assemblies: an experimental and computational study

Abstract: We provide a structure–function relationship study of an organic crystalline photoconductor composed of oppositely charged ionic porphyrins Nano to millimeter size crystals with well-defined morphology composed of stoichiometric amounts of meso-tetra(N-methyl-4-pyridyl)porphyrin (TMPyP) and meso-tetra(4-sulfonatophenyl)porphyrin (TSPP) were grown in a controlled and reproducible manner The rod shaped TMPyP:TSPP monoclinic P21/c crystals have a pseudo-hexagonal cross section and their internal structure consists of highly organized molecular columns of alternating porphyrin cations and anions Experimental characterization of the TMPyP:TSPP solid was performed using powder-XRD, AFM, SEM, DRS UV-visible, and photoconductivity measurements For the first time the morphology of an ionic porphyrin solid is predicted The TMPyP:TSPP crystals are non-conducting in the dark but become conductive with illumination The n-type photoconductive response is significantly faster with excitation in the Q-band than with excitation in the Soret band Quantum mechanical calculations were performed to determine the electronic band structure and density of states and to explain the photoconduction in TMPyP:TSPP Based on these results we propose a model in which two types of photoconductivity occur: (1) band conduction which occurs at all excitation wavelengths and (2) hopping conductivity caused by metastable photoinduced defects that form primarily at higher energy excitations This work combines the results from structural and theoretical studies and correlates them with electronic and optoelectronic properties thereby opening the road to the engineering of highly-organized functional materials from organic π-conjugated molecules

Predicting the Size Distribution in Crystallization of TSPP:TMPyP Binary Porphyrin Nanostructures in a Batch Desupersaturation Experiment

Abstract: Crystallization of a binary porphyrin nanostructure (BPN) of TSPP (meso-tetra(4-sulfonatophenyl)porphyrin) and TMPyP (meso-tetra(N-methyl-4-pyridyl)porphyrin) was studied. The morphology and crystallinity of the BPN was investigated using transmission electron (TEM) and atomic force microscopies (AFM). The composition of the BPN was analyzed using X-ray photoelectron spectroscopy (XPS), elemental analysis, and UV–visible spectroscopy. These techniques revealed a 1:1 composition of anionic to cationic porphyrins in the structure. Our initial studies on the synthesis of these materials revealed that the average size of these crystals increases monotonically with synthesis temperature and decreasing monotonically with initial concentration (supersaturation) of the mother solution. In this work we have developed a model to simulate the growth of these organic monocrystalline materials for the first time. This model encompasses all the major kinetic and thermodynamic steps of crystallization including homogene...

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Intramolecular Interactions in the Ground and Excited State of

Abstract: The fluorescent properties of the cationic free base tetrakis(4-N-methylpyridy1)porphyrin (H2TMPyP(4)) in aqueous solution have been the subject of considerable discussion. Conclusions by various authors on the presence of homo-aggregation of H2TMPyP in these solutions are contradictory. The present work reports spectroscopic data for three isomers of H2TMPyP(n) (n = 2,3, or 4) at varying concentrations, solvent polarity, and temperature. 'H NMR spectra of H2TMPyP(4) show no ground-state monomers below M in water. Fluorescence spectra of the three isomers in aqueous solutions indicate the absence of aggregates both in the ground and excited state. Fluorescence lifetimes of the three isomers both in solution as well as adsorbed on solid surfaces can be explained by taking into account their dependence on the steric hindrance for rotation of the pyridinium groups of the three isomers with respect to the porphyrin macrocycle. Molecular mechanics confirms a higher degree of steric hindrance of H2TMPyP(2) as compared to the two other isomers. From the experimental results it is concluded that the first excited singlet state SI of the porphyrin mixes with a nearby CT state slightly above this SI state. In this CT state an electron is transferred from the porphyrin macrocycle to the pyridinium group. The amount of SI-CT mixing, responsible for the spectroscopic differences, is determined by the degree of coplanarity and resonance interaction of the porphyrin and the pyridinium n-systems, and by the solvent polarity which determines the energy difference between the two states.

Inorganic Fillers for Dental Resin Composites: Present and Future.

Abstract: Dental resins represent an important family of biomaterials that have been evolving in response to the needs in biocompatibility and mechanical properties. They are composite materials consisting of mostly inorganic fillers and additives bound together with a polymer matrix. A large number of fillers in a variety of forms (spheroidal, fibrous, porous, etc.) along with other additives have been studied to enhance the performance of the composites. Silane derivatives are attached as coupling agents to the fillers to improve their interfacial properties. A review of the literature on dental composite fillers seems to suggest that each of the fillers tested presents its own strengths and weaknesses, and often combinations of these yield resin composites with the desired balance of properties. Additives such as nanotubes, whiskers, fibers, and nanoclusters have been shown to enhance the properties of these hybrid materials, and their use in small fractions may enhance the overall performance of the dental resi...