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Langford, Steven J.; Lee, Marcia A.-P.; Macfarlane, Katherine J.; Weigold, Josephine A.

doi:10.1023/a:1014494303384

Cited by 29 publications

(29 citation statements)

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“…[26] Importantly, the plane of the NDI is predicted to be almost orthogonal to the plane of the phenolate in each of the energy-minimized structures (Table 1).…”

Section: Full Papermentioning

confidence: 95%

“…[24][25][26] The high charge on the tin centre renders the porphyrin a relatively hard Lewis acid with selectivity for oxo ligands (phenols, carboxylic acids) over softer nitrogenous ligands in solution. [24][25][26][27][28][29][30][31] Importantly for this study, the inductive effect of the high charge on the metal makes tin(IV) porphyrins very stable to ring reduction. [32] In this respect, studies by Reddy and Maiya indicated that ET can occur from a phenolate ligand to the photoexcited porphyrin, the efficiency of which increases with the basicity of the phenolate.…”

Section: Introductionmentioning

confidence: 99%

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Porphyrin‐Based Molecular Rotors as Fluorescent Probes of Nanoscale Environments

Ghiggino

Hutchison

Langford

et al. 2007

Adv Funct Materials

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The synthesis, characterization, and photophysical properties of a series of supramolecular triads consisting of a tin(IV) porphyrin with axial ligands of ortho‐, meta‐, and para‐hydroxyphenyl naphthalenediimides are presented. For the meta‐ and para‐hydroxyphenyl derivatives, efficient and solvent‐viscosity‐dependent quenching of porphyrin fluorescence is observed. Experimental and theoretical studies demonstrate that, in these compounds, photoinduced electron transfer from the phenolate to the porphyrin is modulated by large amplitude rotational motions of the naphthalenediimide. These compounds are novel examples of fluorescent molecular rotors, and their potential use as environmental probes of local viscosity and temperature are discussed.

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“…[26] Importantly, the plane of the NDI is predicted to be almost orthogonal to the plane of the phenolate in each of the energy-minimized structures (Table 1).…”

Section: Full Papermentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Porphyrin‐Based Molecular Rotors as Fluorescent Probes of Nanoscale Environments

Ghiggino

Hutchison

Langford

et al. 2007

Adv Funct Materials

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“…[5] Tin(IV) porphyrins have been used in supramolecular chemistry due to their spontaneous, chemoselective, covalent strength binding of oxyanions at the six-coordinate tin(IV) metal centre. [6][7][8][9] Many examples also utilise the interesting optical and electronic properties of the tin(IV) porphyrin. [10] These studies have largely generated complexes Abstract: Local molecular environment effects on the rates of ligand exchange at an asymmetric di[dihydroxotin(IV)] bis-porphyrin 5 are examined.…”

Section: Introductionmentioning

confidence: 99%

“…[5][6][7][8]11] Subsequently, the protonated hydroxo ligand (water) dissociates and the carboxylate anion may then associate by an ester-like bond at the tin(IV) centre. Once bound at the tin(IV) centre, carboxylate ligands tend only to exchange in the presence of free acid of comparable or greater strength than that bound.…”

Section: Introductionmentioning

confidence: 99%

Regioselective Reactivity of an Asymmetric Tetravalent Di[dihydroxotin(IV)] Bis‐Porphyrin Host Driven by Hydrogen‐Bond Templation

Brotherhood¹,

Luck²,

Blake³

et al. 2008

Chemistry A European J

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Local molecular environment effects on the rates of ligand exchange at an asymmetric di[dihydroxotin(IV)] bis-porphyrin 5 are examined. The host 5 possesses four non-equivalent tin(IV)-ligand binding sites that are distinguished by their position relative to a shallow cavity, by the steric environment at each binding site and by electronic-structure differences between the constituent porphyrin and quinoxalinoporphyrin macrocycles. These design features of the asymmetric host are confirmed by X-ray crystal structure analysis. Binding experiments with monodentate carboxylic acids and bidentate dicarboxylic acids show significant differences in the rate of ligand exchange at each of the four tin(IV) binding sites. For monodentate carboxylic acids, binding preferentially occurs at the exterior porphyrin site. Further addition of carboxylic acid results in sequential binding at the quinoxalinoporphyrin sites and lastly at the interior site on the porphyrin, with high regioselectivity. These selective binding outcomes are immediately apparent by NMR spectroscopy. A series of 2D NMR spectroscopy experiments allowed identification of the preferred binding sites at the host. This positively identifies that steric hindrance and electron-withdrawing functionality on the porphyrin macrocycle impede ligand exchange. However, these effects are overcome by dicarboxylic acid guests, which form ditopic hydrogen-bond interactions between the intracavity hydroxo ligands in the initial stage of ligand exchange, leading to regioselective binding between the tin(IV) sites within the cavity. It is envisaged that the factors identified herein that define regioselective ligand exchange at host 5 will find wider application in supramolecular systems incorporating tin(IV) porphyrins.

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“…A mechanism for the addition of the carboxylic acid has been proposed by us previously, [3] and has subsequently been applied to the addition of alcohols to Sn-porphyrins. [14] As carboxylate ligands are in slow exchange with Sn porphyrins on the NMR timescale, their protons always give sharp, well-defined resonances at room temperature. [3] Fur- band, but one which was too small (1 ± 2 nm) to allow ligand exchange to be conveniently monitored by UV spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Carboxylate Complexes of Sn^IV Porphyrin Monomers and Oligomers

Hawley

Bampos

Sanders

2003

Chemistry A European J

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Most of the porphyrin-recognition chemistry we have investigated previously has centred on kinetically labile metal-ligand interactions, such as Z-N and Ru-N. Our interest in the broader scope of molecular recognition required a metal with the ability to specifically recognise non-nitrogen-based ligands, with a significantly different binding interaction to distinguish it from nitrogen-based analogues. In this report we describe interactions of Sn(IV) porphyrins that bind oxygen-based ligands and for which the Sn(IV)bond;O bond is in slow exchange on the NMR timescale. A series of carboxylate complexes is employed to highlight the structural/geometric features of porphyrin monomers and cyclic oligomers. Where more than one porphyrin unit is present in a molecular scaffold, we report the effect of carboxylate binding on the complex when the two porphyrins contain different metals (typically Sn(IV) and Zn(II)). The unexpected spectroscopic and structural properties of the Sn(2)(9-anthroic acid)porphyrin dimer are also reported.

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Cited by 29 publications

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Porphyrin‐Based Molecular Rotors as Fluorescent Probes of Nanoscale Environments

Porphyrin‐Based Molecular Rotors as Fluorescent Probes of Nanoscale Environments

Regioselective Reactivity of an Asymmetric Tetravalent Di[dihydroxotin(IV)] Bis‐Porphyrin Host Driven by Hydrogen‐Bond Templation

Synthesis and Characterization of Carboxylate Complexes of Sn^IV Porphyrin Monomers and Oligomers

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Untitled

Cited by 29 publications

References 1 publication

Porphyrin‐Based Molecular Rotors as Fluorescent Probes of Nanoscale Environments

Porphyrin‐Based Molecular Rotors as Fluorescent Probes of Nanoscale Environments

Regioselective Reactivity of an Asymmetric Tetravalent Di[dihydroxotin(IV)] Bis‐Porphyrin Host Driven by Hydrogen‐Bond Templation

Synthesis and Characterization of Carboxylate Complexes of SnIV Porphyrin Monomers and Oligomers

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Synthesis and Characterization of Carboxylate Complexes of Sn^IV Porphyrin Monomers and Oligomers