Synthesis, Structure, and Modeling of a Cyclic Rhodium(III) Porphyrin Dimer with an Encapsulated 4,4‘-Bipyridine Ligand

Kim, Hee-Joon; Redman, James E.; Nakash, Moshe; Feeder, Neil; Teat, Simon J.; Sanders, Jeremy K. M.

doi:10.1021/ic990593i

Cited by 34 publications

(41 citation statements)

References 56 publications

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“…5,15-Bis(4-methoxycarbonyl-phenyl)-2,8,12,18-tetrahexyl-3,7,13,17-tetramethyl porphyrin, prepared from 4-formyl-methylbenzoate according to a standard procedure, 63 was metalated using an analogous procedure to the synthesis of 1. 47 The product was obtained as an orange solid (144 mg, 58%) after column chromatography on silica eluted with dichloromethane (DCM (1)2‚DABCO (6). Prepared by titration of a solution of 1 (3.95 mg, 3.5 µmol) in CDCl3 (600 µL) with DABCO in CDCl3.…”

Section: Methodsmentioning

confidence: 99%

“…This was prepared in an identical manner to 2, using 4,4′-bipyrimidine instead of 4,4′-bipyridine. 47 Purification by column chromatography on silica eluting with hexane/DCM (4/3 gradient to 1/1) afforded 8 as an orange solid ( 47 (80 mg, 94 µmol) were refluxed in pyridine (5 mL) under air for 7 h and allowed to cool to room temperature. Water (20 mL) was added, and the red precipitate was filtered onto Celite and washed with MeOH (50 mL).…”

Section: Methodsmentioning

confidence: 99%

“…45, 46 We have described the preparation and crystal structure of a covalently linked Rh(III) porphyrin dimer templated by a 4,4′-bipyridine ligand and the structure of an analogous noncovalently linked complex bridged by 4,4′-bipyridine. 47 We also recently communicated the preparation of heterometallic porphyrin oligomers assembled by complementary Sn-O, Zn-N, and Ru-N coordination chemistry. 48 As it is reported that coordination of amino acids to Rh(III) porphyrins occurs through the amine moiety, and not the carboxylic acid, 45 this suggested to us that a combination of Rh(III) porphyrins and oxophilic Sn(IV) porphyrins would be suitable for construction of heterometallic architectures.…”

Section: Introductionmentioning

confidence: 99%

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Rh(III) Porphyrins as Building Blocks for Porphyrin Coordination Arrays: From Dimers to Heterometallic Undecamers

et al. 2001

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The coordination chemistry of a Rh(III) porphyrin building block was investigated with a view to the construction of heterometallic arrays of porphyrins. The Rh(III) porphyrin was found to coordinate methanol in the solid state and weakly in CDCl(3) solution. Crystallization afforded five coordinate pi stacked Rh(III) porphyrins. The distribution of products from reaction of Rh(III) porphyrin with DABCO, 4,4'-bipyridine, and 4,4'-bipyrimidine could be displaced toward dimeric species by silica gel column chromatography or recrystallization which served to remove excess ligand. Weak coordination to nitriles was observed, although it was sufficiently strong to organize a dimeric complex of 5,5'-dicyano-2,2'-bipyridine in the solid state. Complexes with 4,4'-bipyrimidine and 5,5'-dicyano-2,2'-bipyridine possess uncoordinated chelating nitrogen atoms. Larger heterometallic porphyrin arrays were assembled using a combination of Sn(IV) and Rh(III) porphyrin coordination chemistry. A Sn(IV) porphyrin acted as a core around which were coordinated two isonicotinate groups, carboxylic acid functionalized porphyrins, or porphyrin trimer dendrons. Rh(III) porphyrins were coordinated to pyridyl groups at the periphery of these entities. In this way an eleven porphyrin array, with four different porphyrin metalation states, was assembled. The diamagnetic nature of both the Rh(III) and Sn(IV) porphyrins, the slow ligand exchange kinetics on the NMR time scale, and tight ligand binding permitted the porphyrin arrays to be analyzed by two-dimensional (1)H NMR techniques.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Rh(III) Porphyrins as Building Blocks for Porphyrin Coordination Arrays: From Dimers to Heterometallic Undecamers

et al. 2001

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“…[9] Ruthenium was inserted by using standard ruthenium insertion conditions; triruthenium dodecacarbonyl and the required porphyrin were heated in decalin for 48 h to give the ruthenium porphyrin. [13] Rhodium porphyrins were prepared according to the literature procedure [14] by stirring the porphyrin and Rh(CO) 4 Cl 2 with NaOAc in anaerobic conditions for four hours, and then I 2 was added to give the iodo porphyrin. Bpy was used as purchased from Aldrich.…”

Section: Methodsmentioning

confidence: 99%

Selection and Amplification of Mixed‐Metal Porphyrin Cages from Dynamic Combinatorial Libraries

Stulz

Scott

Bond

et al. 2003

Chemistry A European J

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Mixed metallo-porphyrin cages were selected and amplified from dynamic combinatorial libraries (DCLs) by using appropriate templates. The cages are composed of two bisphosphine substituted zinc(II) porphyrins as ligand donors and two rhodium(III) or ruthenium(II) porphyrins as ligand acceptors, and are connected through metal-phosphorus coordination. Ru and Rh porphyrins that display a large structural diversity were employed. The templating was achieved by using 4,4'-bpy, 3,3'-dimethyl-4,4'-bipyridine and benzo[lmn]-3,8-phenanthroline, and acts through zinc-nitrogen coordination. The absolute amount of amplification from the DCLs is strongly dependent on the combination of the Ru/Rh porphyrin and the template; cages with sterically demanding porphyrins can only form with smaller templates. In the case of tert-butyl-substituted TPP (TPP=tetraphenylporphyrin), cages are not formed at all. The formation of the cages is usually complete within 24 h at an ambient temperature; in the case of the cage containing Rh(III)OEP (OEP=octaethylporphyrin) and bpy, the pseudo-first-order rate constant of cage formation was determined to be 2.1+/-0.1x10(-4) s(-1) (CDCl(3), 25 degrees C). Alternatively, heating the mixtures to 65 degrees C and cooling to room temperature yields the cages within minutes. The (1)H NMR chemical shifts of several characteristic protons show large differences upon changing the identity of the Ru/Rh porphyrin and the central metal; this is most likely to arise from variations in the geometry of the cages. The X-ray crystal structure of a cage, which contains Rh(III)OEP as a porphyrin acceptor and bpy as template, demonstrates that the cages can adopt severely distorted conformations to accommodate the relatively short templates. An extension to mixed DCLs showed that only limited selectivity is displayed by the various templates. Formation of mixed cages that contain two different rhodium porphyrins prevents effective selection, although the kinetic lability of the systems allows for some amplification. This lability, however, also prevents isolation of the individual cages. Removal of the template leads to re-equilibration, thus the templates act as scaffolds to keep the structures intact.

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“…Biological relevance and varied chemical utilities have made porphyrins in their dimeric/oligomeric form very interesting systems [1][2][3][4][5][6][7][8]. Selective positioning of such dimers and tetramers in the protein envelope is crucial in several life processes.…”

Section: Ionically Bound Metalloporphyrin Pairs On Solid Polymer Supportmentioning

confidence: 99%

Ionically bound metalloporphyrin pairs on solid polymer support

Vinodu

Padmanabhan

2001

J. Porphyrins Phthalocyanines

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ABSTRACT:The present work demonstrates a simple and elegant strategy by which synthetically simple porphyrins are grafted on solid polymer support to generate porphyrin pairs held together by strong coulombic forces. Metalloporphyrins of tetra(4-pyridyl)porphyrins (MTPyP) were reacted with chloromethylated polystyrene (PS) beads to get covalently bound monocationic porphyrins on the polymer support (PS-MTPyP ). These were then converted to their tetracationic species (PS-MTMe 3 PyP 4 ) by exhaustive quaternisation, using CH 3 I. IONICALLY BOUND METALLOPORPHYRIN PAIRS ON SOLID POLYMER SUPPORTBiological relevance and varied chemical utilities have made porphyrins in their dimeric/oligomeric form very interesting systems [1][2][3][4][5][6][7][8]. Selective positioning of such dimers and tetramers in the protein envelope is crucial in several life processes. We have demonstrated that considerable electronic and redox tuning of porphyrins is possible by grafting or incorporating them in polymer matrices and also by varying the mode of association between the host matrix and the pigment [9]. We have also attempted to model a few enzyme functions by making use of such a 'polymer effect' and utilising the easy workability of solid polymerimmobilised porphyrins [10][11][12]. In this communication we demonstrate a simple and elegant method by which novel porphyrin pairs could be grafted on a solid polymer surface and present the possibility of generating a wide variety of both homo-and hetero-porphyrin pairs associated through strong coulombic interaction.The strategy for developing the porphyrin pairs involves interacting the surface-functionalised solid polymer with porphyrins having reactive peripheral groups to affect initially a covalent linkage and then converting the grafted porphyrin moieties to tetracationic species and subsequently making them bind coulombically with tetraanionic porphyrins. The reaction process involved in the porphyrin pair generation is depicted in Scheme 1. The polymer support employed for the purpose was Merrifield resin (PS), which is divinylbenzene cross-linked polystyrene functionalised at the surface by chloromethylation containing 2.0 meq of Cl/g of polymer. The porphyrins used for initial grafting were either free-base or metalloderivatives of 5,10,15,20-tetra-4-pyridylporphyrin (MTPyP, M = H 2 , Mn, Cu, Zn, Ag), which were prepared by reported procedures [13,14]. The reaction involved for the grafting process was quaternisation of pyridyl moieties of MTPyP with the surface-CH 2 Cl functions of PS in dimethylformamide (DMF) medium (80°C, 72 h) (Step I in Scheme 1). A typical reaction process involved reacting 1 g of PS with 100 ml of a dilute porphyrin solution of 1 mM strength. The immobilisation of the porphyrin was evident from the characteristic colour formation on the polymer surface, which was persistent and unleachable with any solvent, whether polar or nonpolar, even under boiling condition. Spectrophotometric estimation showed that the extent of MTPyP uptake was in the range ...

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Synthesis, Structure, and Modeling of a Cyclic Rhodium(III) Porphyrin Dimer with an Encapsulated 4,4‘-Bipyridine Ligand

Cited by 34 publications

References 56 publications

Rh(III) Porphyrins as Building Blocks for Porphyrin Coordination Arrays: From Dimers to Heterometallic Undecamers

Rh(III) Porphyrins as Building Blocks for Porphyrin Coordination Arrays: From Dimers to Heterometallic Undecamers

Selection and Amplification of Mixed‐Metal Porphyrin Cages from Dynamic Combinatorial Libraries

Ionically bound metalloporphyrin pairs on solid polymer support

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