Chiral self-sorted multifunctional supramolecular biocoordination polymers and their applications in sensors (original) (raw)
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Reversible Optical Transcription of Supramolecular Chirality into Molecular Chirality
Science, 2004
In nature, key molecular processes such as communication, replication, and enzyme catalysis all rely on a delicate balance between molecular and supramolecular chirality. Here we report the design, synthesis, and operation of a reversible, photoresponsive, self-assembling molecular system in which molecular and supramolecular chirality communicate. It shows exceptional stereoselectivity upon aggregation of the molecules during gel formation with the solvent. This chirality is locked by photochemical switching, a process that is subsequently used to induce an inverted chiral supramolecular assembly as revealed by circular dichroism spectroscopy. The optical switching between different chiral aggregated states and the interplay of molecular and supramolecular chirality offer attractive new prospects for the development of molecular memory systems and smart functional materials.
ACS Omega, 2017
A novel dioxa[6]helicene-based supramolecular chirogenic system (1) as a specific chiral recognition host for enantiopure trans-1,2-cyclohexanediamine (2) is reported. Host 1 with an inherent free phenolic group and a (1S)-camphanate chiral handle on the opposite terminal rings of the helicene chromophore acted as an efficient turn on fluorescent sensor for S,S-2 with an excellent enantioselective factor, α = K SS /K RR = 6.3 in benzene. This specific host−guest interaction phenomenon is found to be solvent-dependent, which leads to an enantioselective chiral (camphanate) group transfer to the diamine guest molecule. In the case of R,R-2, the de value is up to 68% even at room temperature. Intriguingly, the induced helicity in dioxa[6]helicene diol 6, upon supramolecular hydrogen-bonding interactions, is of opposite sense with positive helicity for S,S-2 and negative helicity for R,R-2, as shown by circular dichroism spectroscopy and in combination with theoretical calculations. This chiral supramolecular system is found to be an excellent host−guest pair for enantiomeric recognition of 2, based on their electronic and steric factors.
Angewandte Chemie (International ed. in English), 2017
The newly developed oligophenylenevinylene (OPV)-based fluorescent (FL) chiral chemosensor (OPV-Me) for the representative enantiomeric guest, 1,2-cyclohexanedicarboxylic acid (1,2-CHDA: RR- and SS-form) showed the high chiral discrimination ability, resulting in the different aggregation modes of OPV-Me self-assembly: RR-CHDA directed the fibrous supramolecular aggregate, whereas SS-CHDA directed the finite aggregate. The consequent FL intensity toward RR-CHDA was up to 30 times larger than that toward SS-CHDA. Accordingly, highly enantioselective recognition was achieved. Application to the chirality sensing was also possible: OPV-Me exhibited a linear relationship between the FL intensity and the enantiomeric excess through the morphological development of stereocomplex aggregates. These results clearly show that the chiral recognition ability is manifested by the amplification cascade of the chirality difference through self-assembly.
CrystEngComm, 2011
New supramolecular luminescent host systems based on 2-cyano-3(4-(diphenylamino)phenyl) acrylic acid (CDPA), a triphenylamine based luminescent acid, and amines (propylamine (1), dimethylaminopyridine, DMAP (2) and (1S,2R)-2-amino-1,2-diphenylethanol (3)) were prepared using a supramolecular approach. For each, the inclusion of amines in the CDPA matrix led to blue shifts in the solid state luminescence. 1 forms a CH 3 CN-selective, luminescent host and exhibits solvent dependent luminescent changes in the solid state. Crystallisation of CDPA-DMAP from EtOAc (2a) and CH 3 CN (2b) produces two different solid forms which exhibit slight differences in luminescence (l max at 522 nm and 529 nm, respectively). The chiral luminescent host system (3a) obtained from CH 3 CN shows robust, reversible CH 3 CN-selective luminescent sensing (l max at 523 nm (with CH 3 CN) and 553 nm (without CH 3 CN)). In this case the luminescence changes with the crystallising solvent (MeOH (3b) and EtOH (3c)).
Chemistry – A European Journal, 2013
FULL PAPER extremely useful molecular platform with applications ranging from organic electronics to biomedicine. [12] The possibility of selective imide functionalization, high p-acidity, planarity conducive to strong p-p interactions, and ease of pro-A C H T U N G T R E N N U N G cessability of these systems in solution has led to increased demand for the design of novel NDI-based supramolecular systems. Imide substituents studied have included alkyl chains, aromatic rings, amino acids, dipeptides, and a combination of alkyl chains and amino acids. [13-21] Our recent work demonstrated the potential of a biomimetic strategy based on amino acid-and peptide-functionalized NDIs for designing 0D, 1D, and 2D molecular materials with interesting structural and functional properties. [12e, 20, 21] The functional relevance of these biomimetic molecular materials varied from attolitre containers for miniaturized biological assays to organic electronics to self-cleaning functional molecular materials. [12e, 20] Furthermore, the amino acid-and dipeptidefunctionalized NDIs emphasized the significance of the chiral centre of the amino acid directly attached to the imide nitrogen in controlling the supramolecular helical chirality of the derived self-assembled structures. [21] Subsequently, the chiroptical properties of these systems revealed significant chiral transcription, amplification, and retentive helical memory with probable implications for the origin of homochirality in Nature. [1c] Cyclic dipeptides (CDPs) are the smallest possible cyclic forms of peptides and are known for their unique structural properties and diverse biological functions. [22] By virtue of their structural rigidity, propensity for strong intermolecular hydrogen bonding, molecular recognition, and resistance towards proteolytic enzymes, CDPs constitute good supramolecular synthons for the preparation of soft organogels, hydrogels, and well-defined nanoarchitectures for various applications. [23-25] We envisaged an inclusive molecular design based on NDI with CDP chiral auxiliaries as monomers for the noncovalent synthesis of helical supramolecular polymers. The NDI-CDP (NCDP) conjugates serve as model systems to evaluate the role of chiral centres on the imide substituents located several atoms away from the imide nitrogen in inducing specific helical assemblies of NDI. This study complements our earlier work, in which the chiral centre of the first amino acid directly attached as the imide substituent through the a-amino group was found to determine the outcome of the helical assembly of NDIs. [20, 21] The NCDP molecular platform has also assisted our understanding of the influence of a-substituents and the corresponding chiral centres in CDP auxiliaries. Herein, we report novel symmetrical NCDPs (1-6) as new molecular platforms to engineer NDI chiral assembly through aromatic (NDI) and hydrogen-bonding (CDP) interactions. Furthermore, this study emphasizes the significance of chiral auxiliaries and the decisive role played by solvent composition in modulating the helical supramolecular self-assembly of such systems.
Functional Chirality: from Small Molecules to Supramolecular Assemblies
Symmetry, 2022
Many structures in nature look symmetric, but this is not completely accurate, because absolute symmetry is close to death. Chirality (handedness) is one form of living asymmetry. Chirality has been extensively investigated at different levels. Many rules were coined in attempts made for many decades to have control over the selection of handedness that seems to easily occur in nature. It is certain that if good control is realized on chirality, the roads will be ultimately open towards numerous developments in pharmaceutical, technological, and industrial applications. This tutorial review presents a report on chirality from single molecules to supramolecular assemblies. The realized functions are still in their infancy and have been scarcely converted into actual applications. This review provides an overview for starters in the chirality field of research on concepts, common methodologies, and outstanding accomplishments. It starts with an introductory section on the definitions ...
A Hybrid Mechanism in Chiral Discrimination Induced by Crystallization of Supramolecular Compounds
The Journal of Physical Chemistry B, 2012
Host−guest complexes formed in aqueous medium between permethylated β-cyclodextrin (TMβ-CD) and racemic 1-(pfluorophenyl)ethanol (p-F-PE) are studied. The crystalline complexes are characterized and their crystal structures are determined, revealing two sets of solid phases with specific abilities for chiral discrimination: on the one hand, a stable complete solid solution with two independent complexes per asymmetric unit exhibits a limited chiral recognition, and on the other hand, two metastable partial solid solutions with unusual 1:2 host−guest stoichiometries behave as diastereomeric complexes. The structural features of the 1:2 complexes and their study by means of molecular modeling show that these solid phases, described as cocrystals formed between one host−guest inclusion complex and one non-engulfed p-F-PE molecule, present a significant chiral discrimination occurring both inside the cyclodextrin and outside the macrocycle in a crystal lattice cavity. Therefore, the enantioselectivity observed in this system results from an interplay between molecular inclusion in the cyclodextrin and lattice inclusion. To our knowledge, it is the first report of such a hybrid mechanism. An overview of the crystal structures of the literature containing TMβ-CD is also achieved and allows their classification in four structural groups in relation to their crystal packing features.