Chiral nanotechnology

Zhang, Jing; Albelda, M. Teresa; Liu, Yu; Canary, James W.

doi:10.1002/chir.20178

Cited by 172 publications

(120 citation statements)

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“…Therefore chiral nanoparticles have been envisaged to play an important role in science and technology. 14,15 In particular CD active luminescent nanoparticles have a great potential for the development of new chiral nanosensors.Over last years there have also been several reports on semiconductor nanomaterials with tetrapodal morphology. These amazing nanostructures have been of great interest due to their potential use in photovoltaics, 16 in the synthesis of asymmetric nano-assemblies 17 as well as prospective additives for polymer reinforcement.…”

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confidence: 99%

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Chiral luminescent CdS nano-tetrapods

et al. 2010

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The utilisation of chiral penicillamine stabilisers allowed the preparation of new water soluble white emitting CdS nano-tetrapods, which demonstrated circular dichroism in the band-edge region of the spectrum.Semiconductor nanocrystals or quantum dots are remarkable for their size dependent optical and photonic properties, which differ significantly from the bulk material. These unique properties are of great interest for a number of potential applications including biomedical imaging, 1-4 sensing, 5 light-emitting diodes (LEDs), 6 photovoltaics 7 and displays. 8Previously the preparation of new chiral quantum dots which demonstrate circular dichroism (CD) activity was achieved by the microwave synthesis in the presence of the chiral penicillamine stabiliser. 9 In this case the formation of chiral defects in the nanocrystals structure leads both to the defect emission and CD response. 10 More recent reports on chiral CdTe based nanoparticles have also been published. 11,12 There is also a very recent theoretical work, which demonstrated that the electric field of the metal or semiconductor nanoparticle enhances the signal from the chiral stabiliser and other chiral species.13 Chirality is a common occurrence in the natural world and chiral compounds have very important applications in chemistry, biology, pharmacology and medicine. Therefore chiral nanoparticles have been envisaged to play an important role in science and technology. 14,15 In particular CD active luminescent nanoparticles have a great potential for the development of new chiral nanosensors.Over last years there have also been several reports on semiconductor nanomaterials with tetrapodal morphology. These amazing nanostructures have been of great interest due to their potential use in photovoltaics, 16 in the synthesis of asymmetric nano-assemblies 17 as well as prospective additives for polymer reinforcement.18 These materials have also displayed anisotropic emission 19 as a direct result of their morphology. Normally the synthesis of nanotetrapods 18,[20][21][22][23][24][25][26][27][28][29] involves the use of high temperature organic phase reactions or the utilisation of solvothermal approach. The mechanism proposed for the formation of these structures 23 engages the generation of seed nanocrystals that subsequently act as sites for preferential growth of the arms. Evidence for this mechanism may be found in the production of heterostructures using prepared pre-formed seed of one material followed by the use of additional materials to grow the arms. 28,30Here we report new chiral CdS nanotetrapods, which have been produced by heating of a basic aqueous solution of CdCl 2 , thioacetamide and racemic (Rac), D-or L-enantiomeric forms of penicillamine (Pen) under reflux.z Samples of the products have been diluted and examined using UV-VIS and photoluminescence (PL) spectroscopy to analyse the absorbance and emission characteristics of the samples. The absorbance spectra show a defined band edge at approximately 370 nm for both enantiomers of the...

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Chiral luminescent CdS nano-tetrapods

et al. 2010

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“…[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.…”

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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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“…This homochirality in the monomeric sugar building blocks of nucleic acids leads to homochirality in their secondary structures such as the right-handed B-type DNA double helix, and tertiary structures such as those found in catalytic and ribosomal RNAs. DNA itself is finding many applications in nanotechnology [5].…”

Section: Homochiralitymentioning

confidence: 99%

“…Nonetheless, the possibility of alternative scenarios based on elements other than carbon and solvents other than water should be kept in mind [20], and could be of interest in the context of synthetic homochiral supramolecular chemistry and nanoscience. Indeed, nanotechnology is already exploiting materials and devices that benefit explicitly from homochirality at the molecular level [5].…”

Section: Homochiralitymentioning

confidence: 99%

An Introduction to Chirality at the Nanoscale

Barron

2009

Chirality at the Nanoscale

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Chiral nanotechnology

Cited by 172 publications

References 112 publications

Chiral luminescent CdS nano-tetrapods

Chiral luminescent CdS nano-tetrapods

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

An Introduction to Chirality at the Nanoscale

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