Studies on the aggregation-induced emission of silole film and crystal by time-resolved fluorescence technique

In this Letter, the photoluminescence of 1,1,2,3,4,5-hexaphenylsilole (HPS) and poly{1,1-[(1,2,3,4,5-pentaphenylsiloly)oxy]-1-phenyl-1-undecyne} (PS9PA) was studied in detail by time-resolved fluorescence technique to investigate possible mechanisms of their unique aggregation-induced emissions. Enhanced emissions and long lifetimes of HPS and PS9PA films were detected in PMMA matrix compared to those of their solutions. Furthermore, strong fluorescence with nanosecond lifetimes was also obtained in the single crystal of HPS. These results show that intramolecular vibrational and torsional motions can act as efficient nonradiative pathways for the excited states to decay in the solutions and that suppression of these motions by restricting intramolecular vibrations in the solid state leads to enhanced fluorescence

Construction of regio- and stereoregular poly(enaminone)s by multicomponent tandem polymerizations of diynes, diaroyl chloride and primary amines

Polyhydroaminations for the synthesis of stable nitrogen-substituted conjugated polymers with welldefined structures remain a great challenge and the control of the regio- and stereochemistry of the enamine product of the hydroamination is non-trivial. Herein we report an efficient tandem polymerization of alkynes, carbonyl chlorides and primary amines to afford regio- and stereoregular conjugated poly(enaminone)s. The atom-economical one-pot sequential polycoupling–hydroamination polymerization catalyzed by Pd(PPh3)2Cl2/CuI proceeded smoothly under mild conditions, furnishing nitrogensubstituted conjugated polymers with high molecular weights (up to 46 100) and high regio-/stereoregularities (100%) in nearly quantitative yields (up to 99%). The single crystal structure of the model compound, together with the NMR spectra comparison of the model compound and polymers provided direct insight into the stereo selectivity of the polymerization, verifying the sole Z-vinyleneisomer of the polymers. Through the exquisite structural design strategy of the intramolecular hydrogen bond of the resulting hydroamination product, the tautomerization between enamine and imine as well as E/Z isomerization was successfully avoided, providing products with high chemical stability and sole Z-vinylene isomers. The conjugated polymers display excellent solubility in common organic solvents, good film forming ability, and high thermal stability. The hydrogen bond formation of the polymer helps to block the potential photo-induced electron transfer process and the polymer shows a unique aggregation enhanced emission phenomenon: their solutions are weakly emissive, while their nanoaggregates or thin films are brightly emissive. Furthermore, thin films of the polymers enjoy high refractive indices (1.9103–1.6582) in a wide wavelength region of 400–1000 nm, which can be further modulated by UV irradiation. Meanwhile, well-resolved fluorescent photopatterns of the polymers can be fabricated through the UV irradiation of thin films via a copper photomask

Ferrocene-Decorated Hyperbranched Poly(aroxycarbonylphenylene)s: Synthesis, Light Refraction, Photopatterning and Precursor to Magnetic Ceramics

Ferrocene-decorated hyperbranched poly[1,3,5-tri(aroycarbonyl)phenylene]s (hb-PTACPs) are prepared in moderate yields with high molecular weights by one-pot polycyclotrimerization of 4,4'-isopropylidenediphenyl bipropiolate with 4-(ferrocenylmethyl)phenyl propiolate in reflux dimethylformamide. All the polymers are soluble and film-forming. They enjoy high thermal stability and lost little of their weight when heated to 300 °C under nitrogen. Thin solid films of the organometallic polymers shows high refractive indices (RI = 1.7038–1.6295) in the wavelength region of 400–1,700 nm. Ceramization of the organometallic hb-PTACPs at high temperature under inert atmosphere gives iron nanoparticles with high magnetizabilities. The organometallic polymers are readily cross-linked under UV irradiation and pyrolysis of the patterned polymer films produces magnetic ceramic patterns with good shape retention

A fluorescence-switchable luminogen in the solid state: a sensitive and selective sensor for the fast "turn-on" detection of primary amine gas

The emission of pyrrole-substituted benzoic acid can be repeatedly switched between the dark and bright states in the solid state by chemical fuming and heating processes, enabling it to work as a rapid sensitive fluorescent sensor for primary amine detection

Molecular anchors in the solid state: Restriction of intramolecular rotation boosts emission efficiency of luminogen aggregates to unity

Introduction of freely rotatable tetraphenylethene (TPE) to conventional luminophors quenches their light emissions in the solutions but endows the resultant molecules (TPEArs) with aggregation-induced emission characteristics in the condensed phase due to the restriction of intramolecular rotation. High fluorescence quantum yields up to 100% have been achieved in the films of TPEArs

Crafting NPB with tetraphenylethene: a win–win strategy to create stable and efficient solid-state emitters with aggregation-induced emission feature, high hole-transporting property and efficient electroluminescence

N,N′-Di-(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) possesses high thermal and morphological stability and is one of the well-known hole-transporting materials for the fabrication of organic light-emitting diodes (OLEDs). Modification of NPB by the covalent integration of tetraphenylethene (TPE) into its structure dramatically changes its emission behavior: the resulting adduct (TPE–NPB) is highly emissive in the aggregated state, showing a novel phenomenon of aggregation-induced emission (AIE). The adduct is thermally and morphologically stable. Non-doped multilayer electroluminescence (EL) devices using TPE–NPB as an emitting layer were fabricated, which emitted green light with a maximum luminance and current efficiency of 11[thin space (1/6-em)]981 cd m−2 and 11.9 cd A−1, respectively. Even better device performances are observed in the bilayer device without NPB. Our strategy takes the full advantage of the AIE property in the solid state and retains the inherent properties of conventional luminophores. It opens a new avenue in the development of stable and efficient solid-state fluorescent materials for OLED application

Synthesis and self-assembly of tetraphenylethene and biphenyl based AIE-active triazoles

Self-assembly of fluorescent functional materials has attracted increasing interest in the fabrication of optoelectronic and biological nanodevices. Tetraphenylethene (TPE) is a typical dye molecule with aggregation-induced-emission (AIE) characteristics. Melding TPE carrying triple-bond functionality with diazide-containing biphenyl through ''click'' chemistry generates AIE-active luminogens [1,1'-biphenyl]-4,4'-diyl bis(6-(4-(4-(1,2,2-triphenylvinyl)phenyl)-1H-1,2,3-triazol-1-yl) hexanoate) [1(5)] and[1,1'-biphenyl]-4,4'-diyl bis(11-(4-(4-(1,2,2-triphenylvinyl)phenyl)-1H-1,2,3-triazol-1-yl) undecanoate)[1(10)] with solid state efficiencies up to unity. Slow addition of dilute THF solutions of 1(m) (m ¼ 5, 10) into nonsolvents such as n-hexane and water yields self-assembled white wooly solids. TEM and SEM observations reveal the (helical) nanofibrous structure of the aggregates. Upon cooling from their concentrated hot solutions, 1(m) readily precipitate. Meanwhile, they can also form gels at high concentrations. Both precipitates and gels of 1(m) exhibit structures similar to those of the aggregates formed in nonsolvents. These results indicate that 1(m) can facilely self-assemble into high emission efficiency (helical) nanofibers, thus paving the way for their optoelectronic and biological applications

Accuracy of Intraocular Lens Power Calculation Formulas for Highly Myopic Eyes

Purpose. To evaluate and compare the accuracy of different intraocular lens (IOL) power calculation formulas for eyes with an axial length (AL) greater than 26.00 mm. Methods. This study reviewed 407 eyes of 219 patients with AL longer than 26.0 mm. The refractive prediction errors of IOL power calculation formulas (SRK/T, Haigis, Holladay, Hoffer Q, and Barrett Universal II) using User Group for Laser Interference Biometry (ULIB) constants were evaluated and compared. Results. One hundred seventy-one eyes were enrolled. The Barrett Universal II formula had the lowest mean absolute error (MAE) and SRK/T and Haigis had similar MAE, and the statistical highest MAE were seen with the Holladay and Hoffer Q formulas. The interquartile range of the Barrett Universal II formula was also the lowest among all the formulas. The Barrett Universal II formulas yielded the highest percentage of eyes within ±1.0 D and ±0.5 D of the target refraction in this study (97.24% and 79.56%, resp.). Conclusions. Barrett Universal II formula produced the lowest predictive error and the least variable predictive error compared with the SRK/T, Haigis, Holladay, and Hoffer Q formulas. For high myopic eyes, the Barrett Universal II formula may be a more suitable choice

What makes efficient circularly polarised luminescence in the condensed phase: aggregation-induced circular dichroism and light emission

In this contribution, we conceptually present a new avenue to construction of molecular functional materials with high performance of circularly polarised luminescence (CPL) in the condensed phase. A molecule (1) containing luminogenic silole and chiral sugar moieties was synthesized and thoroughly characterized. In a solution of 1, no circular dichroism (CD) and fluorescence emission are observed, but upon molecular aggregation, both the CD and fluorescence are simultaneously turned on, showing aggregation-induced CD (AICD) and emission (AIE) effects. The AICD effect is supported by the fact that the molecules readily assemble into right-handed helical nanoribbons and superhelical ropes when aggregated. The AIE effect boosts the fluorescence quantum efficiency (ΦF) by 136 fold (ΦF, ∼0.6% in the solution versus ∼81.3% in the solid state), which surmounts the serious limitations of aggregation-caused quenching effect encountered by conventional luminescent materials. Time-resolved fluorescence study and theoretical calculation from first principles conclude that restriction of the low-frequency intramolecular motions is responsible for the AIE effect. The helical assemblies of 1 prefer to emit right-handed circularly polarised light and display large CPL dissymmetry factors (gem), whose absolute values are in the range of 0.08–0.32 and are two orders of magnitude higher than those of commonly reported organic materials. We demonstrate for the first time the use of a Teflon-based microfluidic technique for fabrication of the fluorescent pattern. This shows the highest gem of −0.32 possibly due to the enhanced assembling order in the confined microchannel environment. The CPL performance was preserved after more than half year storage under ambient conditions, revealing the excellent spectral stability. Computational simulation was performed to interpret how the molecules in the aggregates interact with each other at the molecular level. Our designed molecule represents the desired molecular functional material for generating efficient CPL in the solid state, and the current study shows the best results among the reported organic conjugated molecular systems in terms of emission efficiency, dissymmetry factor, and spectral stability

Aggregation‐induced emission luminogen: A new perspective in the photo‐degradation of organic pollutants

Both the variety and uniqueness of organic semiconductors has contributed to the rapid development of environmental engineering applications and renewable fuel production, typified by the photodegradation of organic pollutants or water splitting. This paper presents a rare example of an aggregation‐induced emission luminogen as a highly efficient photocatalyst for pollutant decomposition in an environmentally relevant application. Under irradiation, the tetraphenylethene‐based AIEgen (TPE‐Ca) exhibited high photo‐degradation efficiency of up to 98.7% of Rhodamine B (RhB) in aqueous solution. The possible photocatalytic mechanism was studied by electron paramagnetic resonance and X‐ray photoelectron spectroscopy spectra, electrochemistry, thermal imaging technology, ultra‐performance liquid chromatography and high‐definition mass spectrometry, as well as by density functional theory calculations. Among the many diverse AIEgens, this is the first AIEgen to be developed as a photocatalyst for the degradation of organic pollutants. This research will open up new avenues for AIEgens research, particularly for applications of environmental relevance