Photoluminescent energy transfer from poly(phenyleneethynylene)s to near-infrared emitting fluorophores

Efficient Detection and Removal of Polycyclic Aromatic Hydrocarbons Using Cyclodextrin-Modified Cellulose

Covalent functionalization of cellulose with β-cyclodextrin by succinic acid-promoted cross-linking leads to a dual-function material that efficiently promotes proximity-induced energy transfer from polycyclic aromatic hydrocarbons (PAHs) to squaraine fluorophores with high quantum yields, and removes PAHs from aqueous solution through non-covalent binding. This material, which possesses a high functionalization density (0.17 μg/mm² of cyclodextrin on cellulose), promotes energy transfer efficiencies as high as 58 % (for an anthracene donor in combination with a squaraine fluorophore acceptor), and leads to the removal of up to 91 % of a PAH (pyrene) from aqueous solution by mixing of the solution with the functionalized material. Overall, the high performance of this material in both proximity-induced energy transfer and the removal of PAHs from water means that such a method has significant potential impact in a variety of real-world environmental remediation scenarios.

Multimodal Fluorescent Polymer Sensor for Highly Sensitive Detection of Nitroaromatics

Detection of nitroaromatic explosives with high sensitivity and selectivity is extremely important for civilian and military safety. Here, we report the synthesis and multimodal sensing applications of an emissive alanine based dansyl tagged copolymer P(MMA-co-Dansyl-Ala-HEMA) (DCP), synthesized by RAFT copolymerization. The fluorescent co-polymer exhibited high sensitivity and selectivity towards conventional nitroaromatic explosives such as DNT, TNT and TNP in solution at lower range of µM level and also with saturated vapor of NACs. The quantum yield of the co-polymer was measured to be very high (Φf = 77%) which make it an ideal candidate for sensing in solution as well as in vapor phase. The fluorescence signal from DCP copolymer gets significantly quenched upon addition of aliquots of DNT, TNT, and TNP. The Stern-Volmer constant was calculated to be very high. The quenching mechanism was further established by fluorescence up-conversion, time-resolved fluorescence and steady state absorption spectroscopy. The energetics of sensing process was calculated by Density Functional Theory (DFT) studies. We also fabricate a thin film polymer sensor which was able to detect nitroaromatic vapors with high selectivity. This opens up the possibility of building a low-cost and light-weight nitroaromatic explosives sensor for field use.

Rapid and efficient pesticide detection via cyclodextrin-promoted energy transfer

Cyclodextrins facilitate non-covalent fluorescence energy transfer from a variety of pesticides to high quantum-yield fluorophores, resulting in a rapid, sensitive detection scheme for these compounds with detection limits as low as two micromolar. Such a facile detection tool has significant potential applications in agriculture and public health research.

A Low Reabsorbing Luminescent Solar Concentrator Employing π-Conjugated Polymers

A highly efficient thin-film luminescent solar concentrator (LSC) utilizing two π-conjugated polymers as antennae for small amounts of the valued perylene bisimide Lumogen F Red 305 is presented. The LSC exhibits high photoluminescence quantum yield, low reabsorption, and relatively low refractive indices for waveguide matching. A Monte Carlo simulation predicts the LSC to possess exceptionally high optical efficiencies on large scales.

Cyclodextrin-promoted energy transfer for broadly applicable small-molecule detection

Reported herein is the development of non-covalent, proximity-induced energy transfer from small-molecule toxicants to organic fluorophores bound in the cavity of γ-cyclodextrin. This energy transfer occurs with exceptional efficiency for a broad range of toxicants in complex biological media, and is largely independent of the spectral overlap between the donor and acceptor. This generally applicable phenomenon has significant potential in the development of new turn-on detection schemes.

Efficient detection of polycyclic aromatic hydrocarbons and polychlorinated biphenyls via three-component energy transfer

Reported herein is the detection of highly toxic polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) via proximity-induced non-covalent energy transfer. This energy transfer occurs in the cavity of γ-cyclodextrin, and is efficient even with the most toxic PAHs and least fluorescent PCBs. The low limits of detection and potential for selective detection using array-based systems, combined with the straightforward experimental setup, make this new detection method particularly promising.

Surface-immobilized monolayers of conjugated oligomers as a platform for fluorescent sensors design: the effect of exciton delocalization on chemosensing performance

Surface-immobilized monolayers of fluorescent molecular sensors consisting of a short conjugated oligo(p-phenylene ethynylene) core end-capped with an acceptor fluorophore (analyte receptor) display significant signal amplification due to enhanced intermolecular energy transfer within the monolayer. This general phenomenon offers a superior platform for designing ratiometric fluorescent sensors. An example of how this can be used to convert a narrow-range threshold fluorescent pH indicator (fluorescein) to a broad-range ratiometric fluorescent chemosensor is described.