Template-Imprinted Chiral Porphyrin Aggregates

Bellacchio, Emanuele; Lauceri, Rosaria; Gurrieri, Sergio; Scolaro, Luigi Monsù; Romeo, and Andrea; Purrello, Roberto

doi:10.1021/ja9820893

Cited by 150 publications

(95 citation statements)

References 14 publications

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“…The concentration of phenylalanine was checked both in the aggregate solution and in the filtrate by fluorescence (k ex = 218 nm, k em = 284 nm). Here is worth noting that the lowest detectable concentration of Phe is of order of 0.01 lM, while the minimum Phe concentration necessary to induce a chiral structure in the porphyrin hetero-aggregate is of the order of 100 lM [16]. Three further "cleaning" centrifugation steps were performed even after no Phe was detected in the sample.…”

Section: Methodsmentioning

confidence: 99%

“…Taking advantage of the chiral memory approach, we have recently published the non-covalent synthesis of chiral porphyrin hetero-aggregates, templated by polypeptides or aminoacids. [16][17][18] These aggregates keep memory of the imprinted chirality that is maintained, even after removing the chiral template. Furthermore, their interactions in the absence of chiral templates leads to achiral species.…”

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confidence: 99%

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Supramolecular Structure of Extrinsically Chiral Porphyrin Hetero‐Assemblies and Achiral Analogues

et al. 2007

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Nature uses chiral information to achieve the excellent degree of selection and efficiency peculiar to all living systems. But chirality is also receiving growing interest for the possible technological applications that span from chiroptical devices [1] to asymmetric catalysis, [2] memory systems, [3,4] and others.[5]The transfer of chiral information to achiral molecules through non-covalent interactions, expressed at a supramolecular level, has, in particular, gained great consideration. [6,7] In fact, non-covalent synthesis, especially when molecular recognition and self-assembly processes are involved, [8] presents many advantages: i) it is not time consuming, ii) it does not lead to side products, and iii) it dose not require an external energy source for reaction. When a chiral structure is imprinted onto an assembly of symmetric molecules by a chiral template or by macroscopic forces (i.e. mechanical effects), [9,10] through mere non-covalent interactions, the resulting supramolecular chiral system may experience two different fates following the template chiral structure modification or removal: i) if the species is under thermodynamic control, it loses the imprinted chiral properties but, ii) if the species is kinetically inert, then it can preserve the imprinted chiral properties for hours, months or even longer. The last case is defined as "memory" effect. [11][12][13] The chiral memory phenomenon is of particular interest because, used in combination with the non-covalent strategy, permits to assembly supramolecular species able to perform predetermined functions coupled with chiral discrimination. [14,15] With these premises, it is clear that understanding the forces involved and the mechanism accompanying induction, modulation and memory of supramolecular chirality could allow for the rational design and assembly of chiral supramolecular systems. Taking advantage of the chiral memory approach, we have recently published the non-covalent synthesis of chiral porphyrin hetero-aggregates, templated by polypeptides or aminoacids. [16][17][18] These aggregates keep memory of the imprinted chirality that is maintained, even after removing the chiral template. Furthermore, their interactions in the absence of chiral templates leads to achiral species.Here, we present the first structural determination of a porphyrin (chiral) hetero-aggregate through energy dispersive X-ray diffraction analysis (EDXD) because of the poor crystalline character of the aggregates. The achiral components are represented by meso-tetrakis(N-Methylpyridium-4-yl)porphinato-copper(II) (CuT4-cationic) and meso-tetrakis-(4-sulfonatophenyl)porphyrin (H 2 TTPS-anionic), while L-phenilalanine is used as chiral mould. Also, a comparison is reported with the amorphous hetero-aggregate structure that the same porphyrins form in the absence of the chiral template. The aggregation process may involve one type of porphyrin only, the homo-assemblies or homo-aggregates, [19,20] or more porphyrins of different type, [21][22][23] the hetero-assem...

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Supramolecular Structure of Extrinsically Chiral Porphyrin Hetero‐Assemblies and Achiral Analogues

et al. 2007

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“…Such a supramolecular complex can be prepared through a self-assembling process by simple addition of the anionic porphyrin to the preformed binary complex at pH ≈ 3.6 [7], at which the polyglutamic matrix adopts an α-helical conformation. The structure of this complex originates from the geometry of polyglutamic acid in α-helical conformation, as is evident from the fact that the mirror image CD spectrum is obtained when poly-D-glutamate is used instead of poly-L-glutamate [9]. Porphyrin heteroaggregation has also been studied using phenylalanine as the chiral template [2,10,11].…”

Section: Cationic Meso-tetrakis(α-trimethylammonio-ptolyl)porphyrin (mentioning

confidence: 99%

“…The porphyrin assemblies have the capacity for chiral memory, that is, they retain their structure after a change in the conformation of the matrix on increasing the pH to around 12 or upon the addition of the opposite matrix [7,9].…”

Section: Cationic Meso-tetrakis(α-trimethylammonio-ptolyl)porphyrin (mentioning

confidence: 99%

Chiral memory and self-replication study of porphyrin and bilirubin aggregates formed on polypeptide matrices

Julínek

Goncharova

Urbanová

2008

Supramolecular Chemistry

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“…It has two negative charges and forms stable J-and H-aggregates depending on the pH and ionic strength in the system. The TPPS J-and H-aggregates shows the property of induced chirality in many systems, such as multilayer and Langmuir-Schaefer (L-S) films prepared from chiral and achiral molecules, [20][21][22][23] the solutions containing polylutamic acid, polylysine, cationic porphyrin etc., [24][25][26][27][28][29][30] and even by mechanical stirring in solutions. 31 However, there is no report about the reversible chirality of TPPS aggregates in film.…”

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A Supramolecular Chiroptical Switch Based on Chitosan and Anionic Porphyrin Complex Film

Liao

Liu

Huang

2007

Polym J

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ABSTRACT:A supramolecular chiroptical switch based on chitosan and tetrakis (4-sulfonatophenyl) porphine (TPPS) complex films was prepared. The reversible changes of the chirality of the complex films were studied by UV-vis and circular dichroism (CD) spectra. It was found that the chirality of the complex films can be wiped off by being exposed to NH 3 gas and subsequently recovered by being exposed to moist HCl gas. The complex film is stable and can stand at least 20 cycles of the switching to NH 3 and HCl gases. There is no change in the above properties after the complex films were store in the air at room temperature. Chirality is an attractive issue in chemistry, biology, material science etc. and has been studied extensively. [1][2][3][4] The chiral switch, which shows the reversible change in chirality with an external stimulation, is particularly attractive due to the potential applications in data storage and sensor systems.5-9 Many chiral optical switches have been proposed, which are based on photochemically induced interconversions, 10,11 photochemically induced changes in liquid crystals, 12,13 stereoisomers of chiral photoresponsive molecules and chiral supramolecular systems, 14,15 etc. The most attractive one in this filed is the chiral optical supramolecular switch because it is easily controlled. [16][17][18][19] Tetrakis(4-sulfonatophenyl)porphine (TPPS, Figure 1) is a well investigated dye. It has two negative charges and forms stable J-and H-aggregates depending on the pH and ionic strength in the system. The TPPS J-and H-aggregates shows the property of induced chirality in many systems, such as multilayer and Langmuir-Schaefer (L-S) films prepared from chiral and achiral molecules, 20-23 the solutions containing polylutamic acid, polylysine, cationic porphyrin etc., [24][25][26][27][28][29][30] and even by mechanical stirring in solutions. 31 However, there is no report about the reversible chirality of TPPS aggregates in film.Chitosan, a chiral biopolymer, is used widely in many fields, e.g. biomedical 32-34 and chemical materials, 35 textiles, 36 pharmaceutics, 37,38 etc. Chitosan is a cationic polyelectrolyte and can interact with the anionic TPPS. More recently, Synytsya et al.39 studied the interaction of TPPS with chitosan in aqueous solutions at different pH value. The results confirmed that the formation of optically active species of TPPS in the presence of chitosan and the J-and H-aggregates depended on pH value and chitosan concentration. However, no work had been reported on the interactions between TPPS and chitosan on chitosan film.In this paper, the reversible change in chirality of chitosan/TPPS complex films when they are alternatively exposed in moist HCl and NH 3 gases was studied. The morphology of the complex films and the interaction between chitosan and TPPS were discussed. EXPERIMENTALWater-soluble anionic porphyrin TPPS was purchased from Dojindo Laboratories. Chitosan (M n ¼ 100 Kda, the degree of deacetylation was 91 mol %) was received from Professor Yanming D...

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Template-Imprinted Chiral Porphyrin Aggregates

Cited by 150 publications

References 14 publications

Supramolecular Structure of Extrinsically Chiral Porphyrin Hetero‐Assemblies and Achiral Analogues

Supramolecular Structure of Extrinsically Chiral Porphyrin Hetero‐Assemblies and Achiral Analogues

Chiral memory and self-replication study of porphyrin and bilirubin aggregates formed on polypeptide matrices

A Supramolecular Chiroptical Switch Based on Chitosan and Anionic Porphyrin Complex Film

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