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146 results on '"Gunter, Maxwell J."'

2. Photoinduced electron transfer in pi-donor-capped Zn(II) porphyrins and N,N'-dimethyl-4,4'-bipyridinium supramolecular assemblies

Author

Kaganer, Evgeny, Joselevich, Ernesto, Willner, Itamar, Chen, Zhangpin, Gunter, Maxwell J., Gayness, Throne P., and Johnson, Martin R.

Subjects
Electron transport -- Research, Porphyrins -- Research, Chemicals, plastics and rubber industries
Abstract

Research was conducted to examine photoinduced electron transfer in pi-donor-capped Zn(II) porphyrins and N,N'-dimethyl-4,4'-bipyridinium supramolecular assemblies. Results indicate that the formation of the complexes prevents the intersystem crossing of the singlet to the triplet state owing to electron-transfer quenching of the excited state by N,N'-dimethyl-4,4'-bipyridinium, MV2+, in the supramolecular assemblies.

Published
1998

3. Self-assembling porphyrin (2)-catenanes

Author

Gunter, Maxwell J., Hockless, David C.R., Johnston, Martin R., Skelton, Brian W., and White, Allan H.

Subjects
Porphyrins -- Research, Hydrogen bonding -- Analysis, Chemistry
Abstract

Several porphyrin-catenanes are synthesized with the help of a self-assembling process, which is employed for the construction of (2)-catenanes and rotaxanes. Template-directed technique facilitates porphyrin insertion into (2)-catenanes, involvement of pi-pi interaction and hydrogen bonding formations. 1H NMR and FAB-MS are employed to characterize these compounds.

Published
1994

4. Carbon-13 NMR spectroscopy, electron spin distributions, and valence state of pentacoordinate manganese tetraphenylporphyrin complexes

Author

Turner, Peter and Gunter, Maxwell J.

Subjects
Manganese -- Research, Porphyrins -- Analysis, Nuclear magnetic resonance spectroscopy -- Analysis, Chemistry
Abstract

Analysis of pentacoordinate-manganese tetraphenylporphyrin (TPP) complexes provides insights into valence state, electron spin distributions and NMR spectra. The HOMO in TPP complexes is the a2(pi) orbital. The porphyrin-phenyl residue interaction involves asymmetry.

Published
1994

6. Two unusual formate-bridged manganese(III) tetraphenylporphyrin complexes

Author

Turner, Peter, Gunter, Maxwell J., Hambley, Trevor W., White, Allan H., and Skelton, Brian W.

Subjects
Porphyrins -- Research, Chemistry
Abstract

The complexes (TPP Mn HCO2)n and (TPP Mn HCO2)3.6CHCl3 are manganese porphyrin moieties linked by bridging formate ion ligands. The first complex was yielded by washing a CH2Cl2 solution of (TPP)Mn(Cl) with aqueous NaOH solution. The compound consists of (tetraphenylporphinato)manganese(III) complexes joined by formate ligands. The second complex was synthesized from the reaction of (TPP)Mn(OH) in methanol with formic acid. It consists of adjacent trimeric components of the raptured chain with longitudinal and transverse separations of 1.104 and 4.241 Angstrom, respectively.

Published
1992

7. Toward multistation rotaxanes using metalloporphyrin coordination templating

Author

Mullen, Kathleen M. and Gunter, Maxwell J.

Subjects
Porphyrins -- Structure, Porphyrins -- Chemical properties, Porphyrins -- Spectra, Chemical synthesis -- Analysis, Nuclear magnetic resonance spectroscopy -- Analysis, Biological sciences, Chemistry
Abstract

The article presents several methods to perform templated synthesis of rotaxanes incorporating strapped metalloporphyrin moieties as the shuttle unit, with the thread component containing both a neutral diimide and functionalized pyridine moiety. A 1,3-dipolar cycloaddition reaction between azides and alkynes, generating triazole linkers in the thread component of rotaxanes is found to be the most successful method.

Published
2008

8. Dynamic axial ligand-site exchange in facially discriminated ruthenium(II) carbonyl and rhodium(III) halide metalloporphyrins

Author

Gunter, Maxwell J. and Mullen, Kathleen M.

Subjects
Ruthenium -- Structure, Ruthenium -- Chemical properties, Ruthenium -- Spectra, Nuclear magnetic resonance spectroscopy -- Analysis, Porphyrins -- Structure, Porphyrins -- Chemical properties, Porphyrins -- Spectra, Chemistry
Abstract

Studies conducted about a series of six-coordinate [Ru.sup.II](CO)L or [Rh.sup.III]([X.sup.-])L porphyrins, facially differentiated by a naphthoquinol- or hydroquinol-containing strap across one face reveal that ligand migration from one face to other could occur under mild conditions and that ligand-site preference is dependent on the nature of L and [X.sup.-].

Published
2007

9. Molecular Modeling and Synthesis of Novel Bis-porphyrin-Fullerene Supramolecular Complex Designed for Photovoltaic Devices

Author

Margetić, Davor, Officer, David, Gunter, Maxwell J., and Warrener, Ronald N.

Subjects
Physics::Biological Physics, Physics::Atomic and Molecular Clusters, porphyrin, cycloaddition, host-guest
Abstract

Donor-acceptor interactions within fullerene-porphyrin architectures are important for multi-component model systems designed for transmission and process of solar energy. Most of these supramolecular photocurrent-generating devices are based on covalently linked components using fullerenes and porphyrins. The alternative approach is the use of self-assembled supramolecular donor-acceptor (D-A) model systems obtained by metal complexation. . , Here we report computational study of a novel bis-porphyrin-fullerene supramolecular complex 1@C60add designed for photovoltaic devices using quantum-chemical calculations. The study of the electronic properties of the excited states of 1@C60add complex indicates electron transfer from porphyrin to fullerene moiety. In continuation, porphyrin-fullerene supramolecular system 1@C60add was synthetized by self-assembly of bisporphyrin component 1 and C60add and its photophysical properties studied, showing large fluorescence quenching by fullerene moiety.

Published
2009

10. MOLECULAR DESIGN AND HOST-GUEST COMPLEXATION PROPERTIES OF SUPRAMOLECULAR BIS-PORPHYRIN 'MOLECULAR TWEEZERS'

Author

Margetić, Davor, Warrener, Ronald, N., Officer, David, Butler, Douglas, N., Dong, Zemin, Merican, Zul, Hesheng, Tang, and Gunter, Maxwell, J.

Subjects
host-guest, porphyrins, norbornenes
Abstract

A computational study of a series of space separated bis-porphyrin “ molecular tweezers” 1 using the AM1 method has been conducted (Figure 1).[1, 2] It was found that bis-porphyrin systems possessing polycyclic spacers are significantly less rigid than previously thought.[3, 4] Variation of the metal-metal separation distance does not cause a significant energy change thus enabling these molecules to easily adjust to the optimal bonding distance required for complexation of various pyridyl ligands. Binding energies for a series of guests were estimated and indicated that the preferred complexation occurs within the cavity of these molecular tweezers (selective binding). With a help of molecular design, bis-porphyrin 1, having a more flexible framework incorporating two “ molecular hinges” was synthetised. Its complexation with several bis-pyridyl guests was studied by NMR and UV spectroscopy.

Published
2006

12. New porphyrin 4pi-cycloaddition reagents and their use in the preparation of porphyrin-(rigid spacer)-1.10-phenanthrolines in which geometric 'tuning' of the chromophores is a feature

Author

Warrener, Ronald N., Schultz, Austin C., Johnston, Martin R., and Gunter, Maxwell J.

Subjects
Chemical tests and reagents -- Analysis, Porphyrins -- Analysis, Biological sciences, Chemistry
Abstract

New examples of porphyrin-containing reagents which function as 1,3-dipoles are analyzed and their value in rigid structure formation is determined. These porphyrin reagents have more potential for the synthesis of rigid diads as shown by the use of dienophilic porphyrin Diels-Alder reagents in synthesis. Various topologies of the chromophores can be obtained on the rigid alicylic framework of the diad product by employing ACE BLOCK assembly protocol.

Published
1999

34. Multiporphyrin ArraysAssembled Through Hydrogen Bonding.

Author

Alessio, Enzo and Gunter, Maxwell J

Abstract

Although relatively weak in isolation, composite H-bonds can be used as an advantage for the assembly of relatively robust and well-defined arrays of molecular components. Porphyrins, with their inherent symmetry, synthetic accessibility and functionality offer ideal base units for the assembly of multicomponent systems by the reversible yet strong intermolecular forces of H-bonding. The geometric precision and strong directionality of H-bonds between relatively rigid donor and acceptor groups can be incorporated into the architecture of porphyrin supramolecular arrays to produce some remarkably complex high-definition assemblies through simple mixing of the component parts. Nevertheless, the very reversibility which allows for ease of construction becomes problematic in ensuring integrity of structure in solution; temperature, solvent and concentration become increasingly important. Measurement techniques are limited to those which can discriminate between the various possible combinations of the component parts to produce discrete oligomeric or polymeric entities. In many cases the measured properties of the assemblies underlying the reason for their construction in the first place also corroborate their structural integrity. Although H-bonding has been used to construct heterotopic porphyrinic arrays comprising porphyrins integrated with other molecular entities, this review is constrained to those systems which principally result in multiporphyrin arrays, although often templated by non-porphyrinic component parts. [ABSTRACT FROM AUTHOR]

Published
2006
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