Method for enhancing the sensitivity of fluorescent chemosensors: energy migration in conjugated polymers

Threading the Needle: Fluorescent Poly-pseudo-rotaxanes for Size-Exclusion Sensing

“…Formic acid (>95%), 4-dodecylbenzene sulfonic acid (DBSA) (≥95%), m-cresol (≥98%), sodium hydroxide (1 M), indole (≥99%) and n-methyl pyrrole (≥99%) were purchased from Sigma and were used as received. Cucurbit [5]uril, cucurbit [6]uril, cucurbit [7]uril and cucurbit [8]uril were purchased from Strem Chemicals, Inc. and were used without further purification. Deuterium oxide (D2O) and deuterated formic acid (d2-formic acid) was purchased from Cambridge Isotope Laboratories, Inc. and used as received.…”

“…Photoluminescence measurements: PL measurements were performed at room temperature with a Horiba Jobin Yvon SPEX Fluorolog-τ3 fluorimeter (model FL-321, 450 W Xenon lamp) using rightangle conformation for solution-based measurements, and front-face conformation for thin films. Thin films were prepared by spin coating solutions of the respective solutions (PPyV: 10 mg/mL in 50/50 v/v H2O/formic acid ; PPyV-CB [7]: 10 mg/mL of PPyV (ratio 20:1 PPyV r.u. :CB [7]) in 50/50 v/v H2O/formic acid) at 3000 rpm …”

“…5,6 The innate ability of CPs to transport excitons over large distances offers great potential to amplify signals in fluorescent sensors, 7 with the majority of photoluminescence (PL) sensor platforms being electrondonating polymers for the detection of electronaccepting analytes. 5,6,[8][9][10][11] The alternative, or inverse situation utilizing electron-accepting (n-type) semiconducting polymers, is limited by few available materials.…”

“…However we find that the portal of CB [7] is optimal for the threading of PPyV. The PPyV-CB[n] system was further exploited to demonstrate a dual-action sensor platform, combining the PL-responsive behavior demonstrated by PPyV towards electron-rich analytes with the size-exclusion properties imparted by volume of the respective CB[n] cavities.…”

“…The PPyV-CB[n] system was further exploited to demonstrate a dual-action sensor platform, combining the PL-responsive behavior demonstrated by PPyV towards electron-rich analytes with the size-exclusion properties imparted by volume of the respective CB[n] cavities. Thin films of PPyV-CB [7] were found to display reversible photoluminescence quenching when exposed to vapors of the biologically relevant molecule indole which is recovered under ambient conditions, suggesting prospects for new size-exclusion based selective sensory schemes for volatile electron-rich analytes. …”