Blue-emitting pyrene-based aggregates

Valera, Jorge S.; Calbo, Joaquín; Gómez, Rafael; Ortı́, Enrique; Sánchez, Luis

doi:10.1039/c5cc03616j

Cited by 16 publications

(11 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Diffusion-ordered spectroscopy (DOSY) NMR experiments at concentrated (20 mM) and diluted conditions (1 mM) confirm the aggregation of 2 since the diffusion of the sample is slower at 20 mM than for the diluted sample (Figure S4). These findings suggest the lack of efficient π-stacking between the aromatic units but the formation of N–H···OC H-bonds between the amide functional groups. Moreover, a rotating-frame Overhauser effect spectroscopy (ROESY) NMR experiment in a concentrated solution of 2 corroborates that the supramolecular organization of this helicene is only due to the formation of H-bonds between the amides.…”

supporting

confidence: 87%

Supramolecular Polymerization of [5]Helicenes. Consequences of Self-Assembly on Configurational Stability

2018

Self Cite

View full text Add to dashboard Cite

The supramolecular polymerization of [5]helicenes 1 and 2 is investigated. The self-assembly of these helicenes proceeds by the operation of H-bonding interactions with a negligible participation of π-stacking. The enantiopurity of the sample has a dramatic effect on the supramolecular polymerization mechanism since it reverts the isodesmic mechanism for the racemic mixture to a cooperative one for the enantioenriched sample. Noticeably, the formation of supramolecular polymers efficiently increases the configurational stability of 1,14-unsubstituted [5]helicenes.

show abstract

supporting

confidence: 87%

Supramolecular Polymerization of [5]Helicenes. Consequences of Self-Assembly on Configurational Stability

2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…Although for the neutral ligand the pyridyl protons (H a and H b ) experience negligible shifts upon cooling, these protons shift upfield for the protonated form (see comparison in Figures a and c). This distinct pattern suggests a parallel stacking of the protonated monomer units within the aggregate, in contrast to the antiparallel arrangement observed for the neutral form. To determine the aggregation mechanism and the corresponding thermodynamic parameters of L 1 :TFA in MCH, the changes in the chemical shift of H c were monitored upon temperature variation.…”

Section: Resultsmentioning

confidence: 99%

Mechanistic Insights into the Self‐Assembly of an Acid‐Sensitive Photoresponsive Supramolecular Polymer

Kartha

Allampally

Yagai

et al. 2019

Chemistry A European J

View full text Add to dashboard Cite

The supramolecular polymerization of an acid‐sensitive pyridyl‐based ligand (L1) bearing a photoresponsive azobenzene moiety was elucidated by mechanistic studies. Addition of trifluoroacetic acid (TFA) led to the transformation of the antiparallel H‐bonded fibers of L1 in methylcyclohexane into superhelical braid‐like fibers stabilized by H‐bonding of parallel‐stacked monomer units. Interestingly, L1 dimers held together by unconventional pyridine–TFA N⋅⋅⋅H⋅⋅⋅O bridges represent the main structural elements of the assembly. UV‐light irradiation caused a strain‐driven disassembly and subsequent aggregate reconstruction, which ultimately led to short fibers. The results allowed to understand the mechanism of mutual influence of acid and light stimuli on supramolecular polymerization processes, thus opening up new possibilities to design advanced stimuli‐triggered supramolecular systems.

show abstract

“…On the basis of these considerations, we have designed a new, S -chiral dichloro(bis)pyridyl OPE-based Pt(II) complex ( 1 in Scheme , for synthetic details, see the Supporting Information (SI)), in which amide groups are introduced to allow for a more versatile molecular reorganization via H-bonds . Compound 1 self-assembles in solution, under controlled conditions of temperature, concentration, and cooling rate, into two coexisting, stable supramolecular polymers with different molecular packing (slipped vs pseudoparallel) that do not interconvert over time in a period of at least six months.…”

Section: Introductionmentioning

confidence: 99%

Unraveling Concomitant Packing Polymorphism in Metallosupramolecular Polymers

et al. 2019

Self Cite

View full text Add to dashboard Cite

The phenomenon of polymorphism is ubiquitous in biological systems and has also been observed in various types of self-assembled materials in solution and in the solid state. In the field of supramolecular polymers, different kinetic vs thermodynamic self-assembled species may exist in competition, a phenomenon termed as pathway complexity. In these examples, the transient kinetic species often has a very short lifetime and rapidly converts into the thermodynamic product. In this work, we report a π-conjugated Pt(II) complex 1 that self-assembles in nonpolar medium into two competing supramolecular polymers with distinct molecular packing (slipped (A) vs pseudoparallel (B)) that do not interconvert over time in a period of at least six months at room temperature. Precise control of temperature, concentration, and cooling rate enabled us to ascertain the stability conditions of both species through a phase diagram. Extensive experimental studies and theoretical calculations allowed us to elucidate the packing modes of both supramolecular polymorphs A and B, which are stabilized by unconventional N–H···Cl–Pt and N–H···O-alkyl interactions, respectively. Under a controlled set of conditions of cooling rate and concentration, both polymorphs can be isolated concomitantly in the same solution without interconversion. Only if A is annealed at high temperature for prolonged time, does a slow transformation into B then take place via monomer formation. Our system, which in many respects bears close resemblance to concomitant packing polymorphism in crystals, should help bridge the gap between crystal engineering and supramolecular polymerization.

show abstract

Blue-emitting pyrene-based aggregates

Abstract: The supramolecular polymerization of pyrene imidazoles 1 and 2, governed by H-bonding and C-H···π interactions, yields aggregates showing the characteristic bluish emission pattern of pyrene-based monomers.

Cited by 16 publications

References 17 publications

Supramolecular Polymerization of [5]Helicenes. Consequences of Self-Assembly on Configurational Stability

Supramolecular Polymerization of [5]Helicenes. Consequences of Self-Assembly on Configurational Stability

Mechanistic Insights into the Self‐Assembly of an Acid‐Sensitive Photoresponsive Supramolecular Polymer

Unraveling Concomitant Packing Polymorphism in Metallosupramolecular Polymers

Contact Info

Product

Resources

About