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The combination of rapid freeze quenching (RFQ) with resonance Raman (RR) spectroscopy represents a unique tool with which to investigate the nature of short-lived intermediates formed during the enzymatic reactions of metalloproteins. Commercially available equipment allows trapping of intermediates within a millisecond to second time scale for low-temperature RR analysis resulting in the direct detection of metal–ligand vibrations and porphyrin skeletal vibrations in hemoproteins. This chapter briefly discusses RFQ-RR studies carried out previously in our laboratory and presents, as a practical example, protocols for the preparation of RFQ samples of the reaction of metmyoglobin with nitric oxide (NO) under anaerobic conditions. Also described are important controls and practical procedures for the analysis of these samples by low-temperature RR spectroscopy. [ABSTRACT FROM AUTHOR]

Transfer of chirality is an intriguing issue worth studying to understand better the origin of life and for possible technological applications. In the last few years we have been working in this area studying the chain of events that begins with induction, reaches a permanent transfer (chiral memory) and extends in some cases to a (quasi-)reversible situation in which induced and permanently memorized chirality coexists. This can happen thanks to a designed blend of thermodynamics and kinetics. [ABSTRACT FROM AUTHOR]

Various functional phthalocyanines as well as their tetrapyrrole analogs, porphyrins, have been extensively studied as organic semiconductors since the first report of organic field effect transistors (OFETs) in 1986. The large conjugated Π system, excellent photoelectric characteristics, intriguing and unique optical properties, high thermal and chemical stability, and most importantly the easy functionalization of phthalocyanines render them ideal organic semiconductor materials as active layers for OFETs. In this chapter, the semiconducting properties of monomeric phthalocyanines as well as monomeric porphyrins, bis(phthalocyaninato) rare earth double-deckers, and tris(phthalocyaninato) rare earth triple-deckers in terms of their semiconducting nature (p-type, n-type, or ambipolar), carrier mobility, and current modulation reported in the past two decades have been summarized. Theoretical studies toward understanding the relationship between molecular structures as well as molecular electronic structures of phthalocyanines and their semiconducting properties have also been included. [ABSTRACT FROM AUTHOR]

In this chapter, recent progress in the application of phthalocyanines and related tetrapyrrole metal complexes in dye-sensitized solar cell (DSSC) is summarized and analyzed. Three categories of phthalocyanines defined by the connecting positions of anchoring groups, namely symmetrically substituted phthalocyanines, asymmetrically substituted phthalocyanines and axially substituted phthalocyanines, are discussed separately. The effects of the distance of the dye molecule from the surface of the semiconductor nanoparticles, the redox potentials and the directionality of the anchoring groups on the performance of the dyes were reviewed. Porphyrins are good sensitizers to wide band semiconductors too. The performance of these sensitizers is predominantly affected by the nature, the connection position of the anchoring groups and the central metal ions. Modifications on the molecular structure of porphyrin by introducing different groups at different positions aimed at extending the absorption spectra, tuning the electronic configuration of the excited states, and inhibiting the aggregation are reviewed. The application of natural porphyrins as sensitizers in DSSCs is also discussed at the end of this chapter. [ABSTRACT FROM AUTHOR]

The chemistry of fullerenes and carbon nanotubes have highly contributed to the progress in the fundamental and applies science of these nanomaterials over the last 15 years. This review focuses on the non-covalent chemistry of fullerenes and carbon nanotubes with nitrogen and/or oxygen containing heterocyclic molecules such as porphyrin, DNA, protein, peptide and carbohydrate. Not only exohedral but also endohedral functionalization is reviewed, because the above guest molecules can interact with both faces of the carbon nanotubes. New terminology is also proposed in the structural and stereochemistry of carbon nanotubes. [ABSTRACT FROM AUTHOR]

As porphyrins and phthalocyanines possess unique electronic, magnetic and optical properties, supramolecular assembly based on them is subject to intense research targets. Herein, the reviewers focus on the supramolecular architectures of porphyrins, which enable their use as electronic and optical functional materials such as third-order optical susceptibilities, photoenergy conversion systems, and organic field-effect transistors. [ABSTRACT FROM AUTHOR]

Fits to Mössbauer spectra of high-spin iron(II) porphyrinates have been applied to the Fe(II) model compounds octaethylporphyrin(1,2-dimethylimidazole) and tetra-paramethoxyporphyrin(1,2-dimethylimidazole). Mössbauer spectra have been measured on these compounds at 4.2 K in large applied fields. Spin Hamiltonians were used for fitting both the electronic and nuclear interactions. The fits are done by adjusting the Hamiltonian parameters to simultaneously minimize the total χ2 for three different applied fieldsvIn order to get best fits, the EFG tensor need to be rotated relative to the ZFS tensorvA comparative sensitivity analysis of their Spin Hamiltonian parameters has also been done on the ZFS parameters D, and the EFG asymmetry parameter η. The best fits suggest that both systems definitely have a negative quadrupole splitting, and that largest EFG component is tilted far from the z-axis of the ZFS tensor, which is likely to be near the heme normal. [ABSTRACT FROM AUTHOR]