Durch sichtbares Licht und Nahinfrarotstrahlung abbaubare supramolekulare Metallo‐Gele

Abstract

Der lichtempfindliche Rutheniumkomplex [Ru-(bpy) 2 (4AMP) 2 ](PF 6 ) 2 (4AMP = 4-(Aminomethyl)pyridin) wurde über die reaktiven Aminogruppen der durchL icht abspaltbaren 4AMP-Liganden in Polyharnstoff-Organo-oder -Hydrogele eingebaut. Im Dunkeln sind diese Gele sehr stabil. DurchB estrahlen mit sichtbarem Lichto der NIR-Strahlung (letzteres mittels Zweiphotonenabsorption) werden die Ruthenium-Pyridin-Bindungen gespalten, was zum Abbau des supramolekularen Gels führt. Dies ermçglicht eine räumlich und zeitlicha ufgelçste Mikrostrukturierung des Gels mithilfe einer Photomaske oder eines gepulsten NIR-Lasers.

Poly(4-vinylpyridine) as ligand for Au(I) and Zn(II) cations: luminescent metal-containing polymers

“…In the last years, research on transition metal-containing polymers increased significantly. Incorporation of transition metal ions into polymeric materials leads to a change of mechanic, electronic, optic, or magnetic properties [1][2][3][4][5][6][7][8][9]. Different strategies have been exploited to prepare metalcontaining polymers leading to different types of polymers.…”

Counting the Clicks in Fluorescent Polymer Networks

“…[22] Rheological measurements, swelling ratios,gravimetry,calorimetry,and thermal analyses are employed to analyze the bulk properties of gels.T he detailed characterization of networks including the number of crosslinks and structural defects is still challenging.T he high complexity of crosslinked systems hampers their quantitative structural analysis by common solid-state spectroscopic techniques.O ne useful spectroscopic method to monitor network formation is FTIR spectroscopy,s ince kinetic information can be obtained by following changes in transmittance of specific IR bands. [11,12,17] Acquisition of quantitative data by IR spectroscopy often requires very careful sample preparation and ah igh local concentration of the functional groups.A na lternative approach is the use of degradable gels,which can be disassembled chemically [11,23,24] or photochemically, [9,10,25] permitting their analysis by solution-based spectroscopy.F or example,J ohnson and colleagues designed an elegant site-selective network-disassembly system, [23][24][25] allowing the quantification of structural defects present in the original gels by the analysis of obtained degradation fragments.…”

“…[7,8] Gel properties can be tailored by employing light as the trigger for network formation. [6,9] Photochemistry offers unique spatiotemporal control over the gelation process,a llowing customizable patterning [10] and the precise tuning of the degree of crosslinking. [11] Approaches reported for light-induced network formation encompass photoinduced thiol chemistry, [11][12][13][14] photodimerization reactions, [15] photoinitiated radical and cationic polymerization, [16,17] and photoactivated cycloaddition reactions.…”

“…We introduce fluorescence as ap owerful tool to gain quantitative information on the number of crosslinking points in networks by combining the self-reporting properties of NITEC systems [19][20][21] with the concept of network disassembly. [9][10][11][23][24][25] Under UV irradiation, pro-fluorescent tetrazole moieties form ah ighly reactive nitrile imine dipole,w hich undergoes 1,3-dipolar cycloaddition with activated enes. [18] When at rifunctional maleimide serves as the dipolarophile, NITEC produces one fluorescent pyrazoline ring for each link formed ( Figure 1A).…”

Bestimmung der Verknüpfungspunkte in fluoreszenten Polymernetzwerken

“…[7,8] Gel properties can be tailored by employing light as trigger for network formation. [6,9] Photochemistry offers unique spatiotemporal control over the gelation process, allowing customizable patterning [10] and the precise tuning of the crosslinking degree. [11] Approaches reported for light-induced network formation encompass photo-induced thiol chemistry, [11][12][13][14] photo-dimerization reactions, [15] photo-initiated radical and cationic polymerization, [16,17] and photo-activated cycloaddition reactions.…”