Probing the microenvironment of surface-attached pyrene formed by a thermo-responsive oligomer.
We have constructed a novel molecular assembly attached to quartz, oxidized silicon and indium-doped tin oxide coated substrates, where a tethered pyrene derivative is co-immobilized with oligo-N-isopropyl acrylamide (oligo-NIPAM). The addition of tethered oligo-NIPAM to the adlayer creates two different, temperature-dependent microenvironments for the surface-bound pyrene. X-ray photoelectron spectroscopy (XPS) and ellipsometry measurements demonstrate the covalent attachment of both oligo-NIPAM and pyrene in our adlayers. Contact angle results confirm the thermo-responsive nature of the oligo-NIPAM on the substrate surface. Steady-state fluorescence data show that the presence of oligo-NIPAM moieties reduces the extent of pyrene excimer formation and provides different environments for the chromophore at temperatures above and below the phase transition. Fluorescence lifetime decay data on surface-bound pyrene are biexponential, consistent with multiple local environments, regardless of whether tethered oligo-NIPAM is present or not. Quenching studies reveal that we can manipulate the sensing properties of this new film simply by adjusting the conformations of oligo-NIPAM.
School of Chemistry and Materials Science, Shaanxi Normal University, Xi'an 710062, PR China.
Fengting
F
Lü
Yu
Y
Fang
G J
GJ
Blanchard
D000178:Acrylamides / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D011721:Pyrenes / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013499:Surface Properties
D000178:Acrylamides; D011721:Pyrenes; C030984:pyrene; C067295:N-isopropylacrylamide