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Chiral recognition with molecular luminescence is a beneficial but challenging method due to an often lack of dramatic difference in intermolecular interactions between the chiral analyte/substrate pair versus their enantiomeric counterpart. Here we show that the difference in room-temperature phosphorescence (RTP) can be substantially augmented by employing guest-host energy-transfer systems. By covalent attachment of chiral amino compounds to a phthalimide host and a naphthalimide guest, respectively, RTP intensity difference of two orders of magnitude with a detection limit of >98% enantiomeric excess (ee) could be achieved. For example, S-enantiomeric guests in S-enantiomeric hosts produce strong red RTP afterglow while no appreciable RTP could be observed in an S/R guest-host combination. The huge spectroscopic difference in RTP results in conspicuous steady-state and delayed-emission variations, which could easily be discriminated by the naked eye. A generalized concept in solid-state RTP chiral recognition is proposed to expand the application scope of the reported method.

Bacterial cellulose/polyaniline (BC/PANI) nanocomposites display many potential applications in various fields. However, the conductivity and mechanical properties remain a challenge. Here, we developed a novel method to prepare BC/PANI nanocomposites via the chemical grafting of PANI onto epoxy modified BC (EBC), followed by the grafting of polyacrylamide (PAM). For comparison, an in situ BC/PANI sample was also prepared. The grafting reaction between PANI and EBC and the retention of PANI on EBC were confirmed by FTIR, X-ray photoelectron spectroscopy, and elemental analysis. The cross-section morphology of BC transformed into a three-dimensional and continuous network structure with the incorporation of PANI. The effects of epoxy and PAM contents on the morphology, conductivity, and mechanical properties of PANI-g-EBC and PANI-g-EBC3/PAM nanocomposites were investigated. Compared with those of the in situ BC/PANI sample, the conductivity of PANI-g-EBC increased from 0.12 to 1.08 S/cm, while the stress ...

A new strategy is constructed for estimating and screening pKa values among different carbon acids under ambient conditions via the UV-vis absorption spectrum of persistent radical pair originating from an N-substituted naphthalimide (NNI) derivative in the presence of various carbanions in organic solutions

N-Substituted naphthalene diimides (NDIs) were explored as purely organic room temperature phosphorescence (RTP) materials based on the strategy of intramolecular charge-transfer (ICT) mediation. A series of NDIs were designed and investigated for their luminescence properties. All emissive NDIs exhibited similar red RTP (emission range from ~600 to ~800 nm) in solid state media; the quantum yield (QY) of the obtained RTP relies heavily on the N-substitution. From poor to moderate to strong donor moieties, the QY increases but suddenly disappears. First-principle calculations reveal that a “sweet spot” for strong NDI RTP exists: while a suitable charge-transfer state can enhance RTP, a strong donor may cause total triplet quenching through the photo-induced electron transfer (PET) mechanism. Furthermore, combining NDI aggregation effects, we realized the reddest RTP ever reported for purely organic materials (Max emission = 675 nm, QY = 21.7%). Given the red emission, respectable QY and oxygen sensitive properties for some of the NDIs, they were tested as imaging agents for in vivo imaging studies.