Negative Photochromism Based on Molecular Diffusion between Hydrophilic and Hydrophobic Particles in the Solid State

Abstract

A colored hybrid based on a merocyanine adsorbed in a nanoporous-silica-composed dendritic fibrous silica was prepared by adsorption onto the nanoporous silica from a spiropyran solution during UV irradiation (photoinduced adsorption). The obtained red hybrid thus exhibited negative photochromism by visible-light irradiation. The hybrid was further combined with an organophilic clay by a solid-state mixing without using solvent to achieve excellent reversibility of the color change, which was thought to be achieved by molecular diffusion through the two materials, where nanoporous silica and organophilic clay accommodated the colored (merocyanine) and colorless (photogenerated spiropyran) isomers, respectively.

Prevent or Cure—The Unprecedented Need for Self‐Reporting Materials

“…Correspondingly,t he isomerization of the previously introduced spiropyrans (SP,see Section 2.1) into merocyanine (MC) can not only be induced by mechanical forces,but also by,f or example,t emperature,p H, solvation, or light. [193][194][195][196][197][198][199][200] Intriguingly,S P-based self-reporting systems have been developed that respond to several stimuli simultaneously. [46][47][201][202][203][204] Forexample,Qui et al reported the synthesis of poly(hydroxyethyl acrylate) with incorporated SPs,w hich changed color upon light irradiation or swelling in water.…”

“…Correspondingly, the isomerization of the previously introduced spiropyrans (SP, see Section 2.1) into merocyanine (MC) can not only be induced by mechanical forces, but also by, for example, temperature, pH, solvation, or light. [ 193 , 194 , 195 , 196 , 197 , 198 , 199 , 200 ] Intriguingly, SP‐based self‐reporting systems have been developed that respond to several stimuli simultaneously. [ 46 , 47 , 201 , 202 , 203 , 204 ] For example, Qui et al.…”

Vorbeugen oder Heilen – die beispiellose Notwendigkeit von selbstberichtenden Materialien

“…Abbott und Mitarbeiter machten sich solche selbstberichtenden LCs zunutze und erweiterten das Konzept durch die Einführung selbstregulierender Eigenschaften. [192] [193][194][195][196][197][198][199][200] Interessanterweise sind SP-basierte selbstberichtende Systeme entwickelt worden, die auf mehrere Stimuli gleichzeitig reagieren. [46,47,[201][202][203][204] Qui et al berichteten zum Beispiel über die Synthese von Poly(hydroxyethylacrylat) mit eingebauten SPs,d ie bei Lichteinstrahlung oder Schwellung in Wasser ihre Farbe änderten.…”

“…Dementsprechend kann die Isomerisierung der zuvor eingeführten Spiropyrane (SP) (siehe Abschnitt 2.1) zu Merocyanin (MC) nicht nur durch mechanische Kräfte, sondern z. B. auch durch Temperatur, pH‐Wert, Solvatation oder Licht induziert werden [193–200] . Interessanterweise sind SP‐basierte selbstberichtende Systeme entwickelt worden, die auf mehrere Stimuli gleichzeitig reagieren [46, 47, 201–204] .…”

Спектральные Проявления Взаимодействия Наночастиц Диоксида Кремния С Молекулами Фотохромных Соединений

“…В результате ранее выполненных исследований показана возможность получения фотохромных систем с обратным фотохромизмом на основе дендримерных наночастиц диоксида кремния и нитро- [2,3], а также гидроксизамещенных индолиновых спиропиранов [4,5]. Обратный фотохромизм наночастиц диоксида кремния обнаружен и при использовании катионных спиропиранов [6].…”