Four chiral 1,2-diaminocyclohexane (DACH)-based molecules (R,R/S,S-2 and R,R/S,S-4) incorporating 1,8-naphthalimide fluorophores exhibit strong circularly polarized luminescence (CPL) emission signals in common organic solvents. Interestingly, the reversed CPL signals can be observed in the aggregated state, which is due to the orderly aggregation.

In this article, a novel zwitterionic conjugated polyelectrolyte containing tetraphenylethene unit was synthesized via Pd-catalyzed Sonogashira reaction. The resulting polymer (P2), which exhibited typical aggregation-induced emission (AIE) properties, was weakly fluorescent in dilute DMSO solution and showed bright fluorescence emissions when aggregated in DMSO/water mixtures or fabricated into conjugated polymer nanoparticles (CPNs). The nanoparticles from P2 could be prepared by reprecipitation method with an average diameter around 23 nm. Notably, the cell-staining efficiencies of lipid-P2 nanoparticles could be enhanced with lipid encapsulation and these nanoparticles were endocytosed via caveolae-mediated and clathrin-mediated endocytosis pathways. Furthermore, the lipid-P2 nanoparticles with low cytotoxicity, high photostability and efficient cell staining ability could be employed for in vitro detection of Fe³⁺ ions in A549 cells. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1686–1693

The β-diketonate-based achiral polymer P-1 could be synthesized by the polymerization of 3,7-dibromo-2,8-dimethoxy-5,5-dioctyl-5H-dibenzo[b,d]silole (M1) with (Z)−1,3-bis(4-ethynylphenyl)−3-hydroxyprop-en-1-one (M2) via typical Sonogashira coupling reaction. The β-diketonate unit in the main chain backbone of P-1 can further coordinate with Eu(TTA)_x [TTA⁻ = 4,4,4-trifluoro-1-(thiophen-2-yl)butane-1,3-dionate anion, X = 1, 2, 3] to afford corresponding Eu(III)-containing polymer complexes. The resulting achiral polymer complex P-2 (X = 2) can exhibit strong circular dichroism (CD) response toward both N-Boc-l and d-proline enantiomers. The CD signal was preliminarily attributed to coordination induction between chiral N-Boc-proline and the Eu(III) complex moiety. The linear regression analysis of CD sensing shows a good agreement between the magnitude of molar ellipticity and concentration of chiral N-Boc-l or d-proline, which indicates this kind Eu(III)-containing achiral polymer complex can be used as a chiral probe for enantioselective recognition of N-Boc-l or d-proline enantiomers based on Cotton effect of CD spectra. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3080–3086

A novel conjugated polymer P-1 incorporating Ru(II) bis(acetylide) complex and borondipyrromethene (BODIPY) moieties in the main chain was synthesized by Pd-catalyzed Sonogashira coupling reaction of diethynyl substituted BODIPY derivative (M-1) and Ru(II) bis(acetylide) complex (M-2), and the reference polymer P-2 was obtained from the same method as preparation of P-1. Compared with P-2, Ru(II)-containing polymer P-1 shows low-bandgap as 0.87 eV from cyclic voltammetry, and obvious redshifts in both UV–vis absorption and fluorescence spectra. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1686–1692

A novel fluorescence chemosensor 1 based on (R)-binaphthyl-salen can exhibit highly sensitive and selective recognition responses toward Cu²⁺ by "turn-off" fluorescence quench type in THF/H₂O, and Zn²⁺ by "turn-on" fluorescence enhancement type in CHCl₃/CH₃CN, respectively, suggesting that solvents can dramatically affect the responsive properties of salen-based chemosensor. In addition, Cu²⁺ can lead to the most pronounced changes of CD spectra without the influence of solvents, which indicates this kind chemosensor can also be used as a sole Cu²⁺ probe based on CD spectra.

A new (S)-binaphthalene-based polymer (P-1) was synthesized by the polymerization of 5,5′-((2,5-dibutoxy-1,4-phenylene)bis(ethyne-2,1-diyl))bis(2-hydroxy-3-(piperidin-1-ylmethyl) benzaldehyde (M-1) with (S)-2,2′-dimethoxy-(1,1′-binaphthalene)-3,3′-diamine (M-2) through the formation of a Schiff base; the corresponding chiral polymer (P-2) could be obtained by the reduction of polymer P-1 with NaBH₄. Chiral polymer P-1 exhibited a remarkable “turn-on” fluorescence-enhancement response towards (D)-phenylalaninol and excellent enantioselective recognition behavior with enantiomeric fluorescence difference ratios (ef) as high as 8.99. More importantly, chiral polymer P-1 displays a bright blue fluorescence color change upon the addition of (D)-phenylalaninol under a commercially available UV lamp, which can be clearly observed by the naked eye. On the contrary, chiral polymer P-2 showed weaker enantioselective fluorescence ability towards the enantiomers of phenylalaninol.

A novel chiral (S)-BINAM-based fluorescent polymer sensor was designed and synthesized by the polymerization of 4,4′-((2,5-dibutoxy-1,4-phenylene)bis(ethyne-2,1-diyl))-dibenzaldehyde (M-1) with (S)-2,2′-binaphthyldiamine (S-BINAM, M-2) via Schiff's base formation. The resulting helical chiral polymer sensor exhibited remarkable “turn-on” bright blue fluorescence color upon the addition of trivalent metal ions under a commercially available UV lamp; this change can be clearly observed by the naked eye for direct visual discrimination at low concentration. More importantly, the addition of trivalent metal cations can lead to a most pronounced change of CD spectra of the chiral polymer indicating this kind chiral sensor can also be used as a sole probe for selective recognition of trivalent metal cations based on CD spectra. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4070–4075

A novel polymer P-1 is prepared by the reaction of the monomer 5,5′-divinyl-2,2′-bipyridine and Salen-Zn(II) via Heck cross coupling. Interestingly, P-1 can further incorporate with Eu(TTA)₃·2H₂O to generate copolymer P-2 with two different metal centers. P-2 exhibits exceptional dual emissive properties which can be tuned by excitation wavelength. For example, an orange fluorescence can be obtained when P-2 is excited at 430 nm, whereas a red emission with a huge Stoke shift of 57 nm is observed when it is excited at 345 nm. The high wavelength emission can be attributed to Eu(III) (⁵D₀⁷F₂), which is lit by an effective photoinduced energy transfer process between P-1 and the Eu(TTA)₃ complex. The properties of P-2 have led to a better understanding of the energy transfer process between P-1 and Eu(TTA)₃ moieties.

A new series of π-conjugated chiroptical polymers consisting of styryl BODIPYs moieties and (S)-binaphthyl units has been firstly synthesized via Sonogashira polymerization. The resulting polymers were characterized by ¹H NMR spectroscopy, gel permeation chromatography (GPC), UV–Vis absorption spectroscopy, cyclic voltammetry (CV), circular dichroism (CD), and density functional theory (DFT) calculations. The chiral polymers have moderate molecular weights, high solubility in commonly solvents and stable chiroptical conformation. And more importantly, the four chiral polymers can exhibit near-infrared (NIR) emissive and good anisotropic fluorescence. We anticipate these chiral NIR polymers will be useful in biological measurements and cellular imaging where NIR emission is beneficial.

A conjugated polymer was synthesized by the polymerization of 4,7-dibromobenzo[2,1,3]thiadiazole (M-1) with tri{1,4-diethynyl-2,5-bis(2-(2-methoxyethoxy)-ethoxy)}-benzene (M-2) via Pd-catalyzed Sonogashira reaction. The polymer shows strong orange fluorescence. The responsive optical properties of the polymer on various metal ions were investigated through photoluminescence and UV–vis absorption measurements. The polymer displays highly sensitive and selective on-off Hg²⁺ fluorescence quenching property in tetrahydrofuran solution in comparison with the other cations including Mg²⁺, Zn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Cd²⁺, and Pb²⁺. More importantly, the fluorescent color of the polymer sensor disappears after addition of Hg²⁺, which could be easily detected by naked eyes. The results indicate that this kind of polymer sensor incorporating benzo[2,1,3]thiadiazole moiety as a ligand can be used as a novel colorimetric and fluorometric sensor for Hg²⁺ detection. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

A highly efficient organocatalytic enantioselective CS bond formation reaction between simple alkyl thiols and Morita–Baylis–Hillman (MBH) carbonates is described. The optically active α-methylene β-mercapto esters could be obtained under mild reaction conditions with excellent enantioselectivities (up to 97% ee). The broad scope and simple operation make this methodology very practical.

The highly effective and enantioselective sulfenylation of β-keto phosphonates catalyzed by α,α-diaryl-L-prolinols has been developed. The optically active α-sulfenylated β-keto phosphonates could be obtained under mild reaction conditions in good yields (up to 92%) and with excellent enantioselectivities (up to 92% ee).

A novel imidazolium ion-tagged L-proline catalyst has been developed. The asymmetric α-aminoxylation of aldehydes and ketones with excellent enantioselectivities, up to 99% ee, and high yields in ionic liquids has been achieved. The system can be easily recycled and reused for at least six times without significant loss of yields and enantioselectivity.

A chiral polymer incorporating an (R,R)-salen moiety was synthesized by the polymerization of (R,R)-1,2-diaminocyclohexane with 2,5-dibutoxy-1,4-di(salicyclaldehyde)-1,4-diethynyl-benzene by a nucleophilic addition–elimination reaction. The fluorescence responses of the (R,R)-salen-based polymer toward various metal ions were investigated by fluorescence spectra. Compared with other cations, such as Na⁺, K⁺, Mg²⁺, Ca²⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Ag⁺, Cd²⁺, Hg²⁺, and Pb²⁺, Zn²⁺ can lead to a pronounced fluorescence enhancement as high as 7.8-fold together with an obvious blue-shift change of the chiral polymer. More importantly, the fluorescent color of the polymer changed to bright blue instead of weak yellow after addition of Zn²⁺, which can be easily detected by the naked eye. The results indicate that this kind of chiral polymer, incorporating an (R,R)-salen moiety as a receptor in the main chain backbone, can exhibit high sensitivity and selectivity for Zn²⁺ recognition.

Three chiral polymers P-1, P-2, and P-3 could be obtained by the polymerization of (R)-6,6′-dibutyl-3,3′-diiodo-2, 2′-binaphthol (R-M-1), (R)-6,6′-dibutyl-3,3′-diiodo-2,2′-bisoctoxy-1,1′-binaphthyl (R-M-2), and (R)-6,6′-dibutyl-3,3′-diiodo-2,2′-bis (diethylaminoethoxy)-1,1′-binaphthyl (R-M-3) with 4,7-diethynyl-benzo[2,1,3]-thiadiazole (M-1) via Pd-catalyzed Sonogashira reaction, respectively. P-1, P-2, and P-3 can show pale red, blue–green, and orange fluorescence. The responsive optical properties of these polymers on various metal ions were investigated by fluorescence spectra. Compared with other cations, such as Co²⁺, Ni²⁺, Ag⁺, Cd²⁺, Cu²⁺, and Zn²⁺, Hg²⁺ can exhibit the most pronounced fluorescence response of these polymers. P-1 and P-2 show obvious fluorescence quenching effect upon addition of Hg²⁺, on the contrary, P-3 shows fluorescence enhancement. Three polymer-based fluorescent sensors also show excellent fluorescence response for Hg²⁺ detection without interference from other metal ions. The results indicate that these kinds of tunable chiral polybinaphthyls can be used as fluorescence sensors for Hg²⁺ detection. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 997–1006, 2010

Chiral polymer P-1 was synthesized by the polymerization of (R)-5,5′-dibromo-6,6'-di(4-trifluoromethyl- phenyl)-2,2′-bisoctoxy-1,1'-binaphthyl (R-M-1) with 5,5′-divinyl-2,2′-bipyridine (M-2) via Pd-catalyzed Heck reaction. The polymer complexes P-2 and P-3 could be obtained by the bipyridyl coordination of P-1 with Eu(TTA)₃·2H₂O and Gd(TTA)₃·2H₂O (TTA⁻=1-(2-thenoyl)-3,3,3-trifluoroacetonate). The chiral polymer P-1 shows strong blue fluorescence due to the extended -electronic structure between the chiral repeating unit (R)-6,6'-di(4-trifluoromethyl-phenyl)-2,2′-bisoctoxy-1,1'-binaphthyl and the conjugated linker 2,2′-bipyridyl (bpy) group via vinylene bridge. The Eu(III)-containing polymer complex P-2 can not only emit the polymer fluorescence, but also have the characteristic fluorescence of Eu(III) (⁵D₀⁷F₂) under different exciting wavelengths. The Gd(III)-containing polymer complex P-3 only emits the polymer fluorescence. Based on the fluorescent properties of the polymer and RE(III)-containing polymer complexes, it can be concluded that the chiral polymer does not transfer energy to Eu(III) or Gd(III) complex moiety but emits its own fluorescence.

Four analogous binaphthyl compounds (R)-3a-3d containing (R)-3,3′-bis(2-pyridyl) groups were synthesized by the conjugation of (R)-2,2′-dimethoxy-1,1′-binaphthyl-3,3′-diboronic acid [(R)-2] with 2-bromopyridine, 2-bromo-5-methylpyridine, 2-chloro-4-fluoropyridine and 2-chloro-3-(trifluoromethyl)pyridine via Pd-catalyzed Suzuki reactions, respectively. The application of the four chiral ligands in combination with Et₂Zn and Ti(Oi-Pr)₄ to the asymmetric addition of phenylacetylene to various aldehydes has been studied. The results show that (R)-3a and (R)-3b are not good catalysts for the alkynylzinc addition to aldehydes, (R)-3d shows good enantioselectivity only for the alkynylzinc addition to aliphatic aldehydes, and (R)-3c exhibits excellent enantioselectivity for phenylethynylzinc addition to both aromatic and aliphatic aldehydes. All the four chiral ligands produced the opposite configuration of the propargylic alcohols to that of the chiral ligands.