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Volumn 17, Issue 22, 2011, Pages 6061-6066

Hydrogen-bonding directed assembly and gelation of donor-acceptor chromophores: Supramolecular reorganization from a charge-transfer state to a self-sorted state

Author keywords

charge transfer; organogels; self assembly; self sorting; supramolecular chemistry

Indexed keywords

AMIDE FUNCTIONALITIES; CATENANES; CHARGE TRANSFER STATE; CONTROL EXPERIMENTS; CT BANDS; DIRECTED ASSEMBLY; DONOR-ACCEPTORS; FUNCTIONALIZED; GEL STATE; HYDROGEN BONDINGS; METHYLCYCLOHEXANE; METHYLENE GROUPS; MIXED ASSEMBLIES; NON-POLAR SOLVENTS; ORGANOGELS; PHOTOPHYSICAL PROPERTIES; ROTAXANES; SELF-SORTING; SERENDIPITOUS DISCOVERY; SUPRAMOLECULAR MATERIALS; SYNERGISTIC EFFECT; SYNTHETIC ION CHANNELS; TETRACHLOROETHYLENES; THERMODYNAMICALLY STABLE;

EID: 79956143499     PISSN: 09476539     EISSN: 15213765     Source Type: Journal    
DOI: 10.1002/chem.201100606     Document Type: Article
Times cited : (63)

References (83)
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    • A. Wu, L. Isaacs, J. Am. Chem. Soc. 2003, 125, 4831. For self-sorted assembly of donor-acceptor chromophores see
    • (2003) J. Am. Chem. Soc. , vol.125 , pp. 4831
    • Wu, A.1    Isaacs, L.2
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    • note
    • The baseline intensity of the absorption spectra was found to increase with supramolecular reorganization (Figure S3 in the Supporting Information), probably due to opaque nature of the self-sorted gel. This caused difficulty in monitoring the CT-band intensity as a function of time and thus we followed the increase in the baseline intensity itself at 700 nm, which arises due to scattering to approximately quantify the transformation rate under various conditions with a assumption that the rate of switching is proportional to the change in scattering intensity.
  • 71
    • 79956061586 scopus 로고    scopus 로고
    • note
    • 3 and MCH) variation in IR spectrum of the individual chromophores clearly indicated hydrogen bonding; see Figure S4 in the Supporting Information for detail.
  • 73
    • 77951544518 scopus 로고    scopus 로고
    • For a recent report on related computational studies see
    • For a recent report on related computational studies see:, S. De, D. Koley, S. Ramakrishnan, Macromolecules 2010, 43, 3183.
    • (2010) Macromolecules , vol.43 , pp. 3183
    • De, S.1    Koley, D.2    Ramakrishnan, S.3
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    • note
    • The present calculation is limited by the fact that we have not included solvents Nevertheless, we believe this provides valuable supporting information regarding the geometrical constraints for hydrogen bonding in case of CT gel formation due to miss-match in distance. As here we are only concerned about structural aspects and not the energetic ones, we assume exclusion of solvents does not have much influence on our conclusions. Moreover, all the gelating solvents have very low dielectric constant, hence it is expected that a gas-phase structure would be very similar. More detailed calculations with extended D-A stacks and including solvent molecules are underway and will be published in a subsequent full paper.
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    • note
    • -1 above the previously discussed structure and in this structure only a single intermolecular hydrogen bond (2.09 à) between the two interacting moieties could be noted. However, under no circumstances could we arrive at a minimum in which both the amide bonds could be involved in strong hydrogen bonding for the alternate stack of NDI-2 and DAN-2. This corroborates well with the experimental observation, that for this D-A pair we always observed self-sorting and no alternate co-stacking. Alternatively, the distance in D- D aggregates also display slightly longer intermolecular hydrogen bond lengths than their A-A counterparts, but generally slightly shorter than the corresponding D-A species (Figure S8 in the Supporting Information).
  • 76
    • 79956154747 scopus 로고    scopus 로고
    • note
    • To confirm that the observed CT gel in TCE is not contaminated with individual self-assembly of A and D, we examined the effect of cooling rate on the CT band of the gel (Figure S2 in the Supporting Information); no notable differences were observed. This indirectly supports the hypothesis that only the CT state is formed during gelation. If there were other types of the self-assembly, the relative mole fractions of various types of structures are expected to vary as a function of cooling speed. However, we realize that this is only indirect evidence and does not completely rule out the possibility of co-existence of the CT and self-sorted states. More detail studies to understand these aspects are underway in our laboratory.
  • 82
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    • note
    • In this case reorganization also happens in MCH and other hydrocarbon solvents. Detailed kinetics studies are underway to gain further insight.
  • 83
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    • note
    • The stable CT state was also observed in other non-polar chlorinated solvents (Table S2 in the Supporting Information).


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.