@article{KarGehrigAllampallyetal.2016, author = {Kar, Haridas and Gehrig, Dominik W. and Allampally, Naveen Kumar and Fern{\´a}ndez, Gustavo and Laquai, Fr{\´e}d{\´e}ric and Ghosh, Suhrit}, title = {Cooperative supramolecular polymerization of an amine-substituted naphthalene-diimide and its impact on excited state photophysical properties}, series = {Chemical Science}, volume = {7}, journal = {Chemical Science}, number = {2}, doi = {10.1039/c5sc03462k}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191459}, pages = {1115-1120}, year = {2016}, abstract = {A donor-acceptor-donor (D-A-D) type naphthalene-diimide (NDI-H) chromophore exhibits highly cooperative J-aggregation leading to nanotubular self-assembly and gelation in n-decane, as demonstrated by UV/Vis, FT-IR, photoluminescence and microscopy studies. Analysis of temperature-dependent UV/Vis spectra using the nucleation-elongation model and FT-IR data reveals the molecular origin of the cooperative nature of the self-assembly. The supramolecular polymerization is initiated by H-bonding up to a degree of polymerization similar to 20-25, which in a subsequent elongation step promotes J-aggregation in orthogonal direction leading to possibly a sheet-like structure that eventually produces nanotubes. Time-resolved fluorescence and absorption measurements demonstrate that such a tubular assembly enables very effective delocalization of excited states resulting in a remarkably prolonged excited state lifetime.}, language = {en} } @article{RestMayoralFernandez2013, author = {Rest, Christina and Mayoral, Mar{\´i}a Jos{\´e} and Fern{\´a}ndez, Gustavo}, title = {Aqueous Self-Sorting in Extended Supramolecular Aggregates}, series = {International Journal of Molecular Sciences}, volume = {14}, journal = {International Journal of Molecular Sciences}, number = {1}, doi = {10.3390/ijms14011541}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-129435}, pages = {1541-1565}, year = {2013}, abstract = {Self-organization and self-sorting processes are responsible for the regulation and control of the vast majority of biological processes that eventually sustain life on our planet. Attempts to unveil the complexity of these systems have been devoted to the investigation of the binding processes between artificial molecules, complexes or aggregates within multicomponent mixtures, which has facilitated the emergence of the field of self-sorting in the last decade. Since, artificial systems involving discrete supramolecular structures, extended supramolecular aggregates or gel-phase materials in organic solvents or—to a lesser extent—in water have been investigated. In this review, we have collected diverse strategies employed in recent years to construct extended supramolecular aggregates in water upon self-sorting of small synthetic molecules. We have made particular emphasis on co-assembly processes in binary mixtures leading to supramolecular structures of remarkable complexity and the influence of different external variables such as solvent and concentration to direct recognition or discrimination processes between these species. The comprehension of such recognition phenomena will be crucial for the organization and evolution of complex matter.}, language = {en} } @article{BaeumerKarthaAllampallyetal.2019, author = {B{\"a}umer, Nils and Kartha, Kalathil K. and Allampally, Naveen Kumar and Yagai, Shiki and Albuquerque, Rodrigo Q. and Fern{\´a}ndez, Gustavo}, title = {Kontrolle {\"u}ber Selbstassemblierung durch Ausnutzung von Koordinationsisomerie}, series = {Angewandte Chemie}, volume = {131}, journal = {Angewandte Chemie}, number = {44}, doi = {10.1002/ange.201908002}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-212176}, pages = {15772 -- 15776}, year = {2019}, abstract = {Hierin wird die inh{\"a}rente geometrische Isomerie eines PtII Komplexes als neues Werkzeug zur Kontrolle von supramolekularen Assemblierungsprozessen ausgenutzt. Bestrahlung mit UV-Licht sowie die sorgf{\"a}ltige Auswahl des verwendeten L{\"o}sungsmittels, der Temperatur und Konzentration f{\"u}hren zu einer regelbaren Koordinationsisomerie. Dies erm{\"o}glicht ein vollst{\"a}ndig reversibles Schalten zwischen zwei definierten aggregierten Spezies (1D Fasern ↔ 2D Lamellen) mit unterschiedlichem photoresponsivem Verhalten. Unsere Erkenntnisse erweitern nicht nur die Reichweite von Koordinationsisomerie, sondern er{\"o}ffnen auch aufregende M{\"o}glichkeiten zur Entwicklung neuartiger stimuliresponsiver Materialien.}, language = {de} } @article{RestPhilipsDuennebackeetal.2020, author = {Rest, Christina and Philips, Divya Susan and D{\"u}nnebacke, Torsten and Sutar, Papri and Sampedro, Angel and Droste, J{\"o}rn and Stepanenko, Vladimir and Hansen, Michael Ryan and Albuquerque, Rodrigo Q. and Fern{\´a}ndez, Gustavo}, title = {Tuning Aqueous Supramolecular Polymerization by an Acid-Responsive Conformational Switch}, series = {Chemistry - A European Journal}, volume = {26}, journal = {Chemistry - A European Journal}, number = {44}, doi = {10.1002/chem.202001566}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218118}, pages = {10005 -- 10013}, year = {2020}, abstract = {Besides their widespread use in coordination chemistry, 2,2'-bipyridines are known for their ability to undergo cis-trans conformational changes in response to metal ions and acids, which has been primarily investigated at the molecular level. However, the exploitation of such conformational switching in self-assembly has remained unexplored. In this work, the use of 2,2'-bipyridines as acid-responsive conformational switches to tune supramolecular polymerization processes has been demonstrated. To achieve this goal, we have designed a bipyridine-based linear bolaamphiphile, 1, that forms ordered supramolecular polymers in aqueous media through cooperative aromatic and hydrophobic interactions. Interestingly, addition of acid (TFA) induces the monoprotonation of the 2,2'-bipyridine moiety, leading to a switch in the molecular conformation from a linear (trans) to a V-shaped (cis) state. This increase in molecular distortion along with electrostatic repulsions of the positively charged bipyridine-H\(^{+}\) units attenuate the aggregation tendency and induce a transformation from long fibers to shorter thinner fibers. Our findings may contribute to opening up new directions in molecular switches and stimuli-responsive supramolecular materials.}, language = {en} }