Recently, graphene-based materials have become well-known nonlinear optical materials for the potential application of laser protection. Two new graphene oxide–platinum  complex (GO–Pt) hybrid materials (GO–Pt-1, GO–Pt-2) have been fabricated through covalent modification and electrostatic adsorption of different Pt complexes with GO. The structural and photophysical properties of the resultant hybrid materials were studied. The nonlinear optical properties and optical power limiting (OPL) performance of Pt complexes, GO, and GO–Pt hybrid materials were investigated by using Z-scan measurements at 532 nm. At the same transmittance, the results illustrate that functionalization of GO makes GO–Pt hybrid materials possess better nonlinear optical properties and OPL performance than individual Pt complexes and GO due to a combination of nonlinear scattering, nonlinear absorption, and photoinduced electron and energy transfer between GO and Pt complex moieties. Furthermore, the nonlinear optics and OPL performance of GO–Pt-2 are better than those of GO–Pt-1, due to not only the excellent optical limiting of Pt-2 and more molecules per area of GO but also the way of combination of Pt-2 and GO.Keywords: graphene oxide; nonlinear optics; optical limiting; photophysics; Pt complex;

•Three Pt(II) complexes bearing BODIPY acetylide ligands were designed and synthesized.•All complexes exhibit significant AIE and OPL properties.•Emission intensity and triplet excited state lifetime increase when nanoparticles formed.A series of Pt(II) complexes bearing difluoro-boron-dipyrromethene (Bodipy) acetylide ligands and different alkyl/aryl substituted 2,2′-bipyridyl ligands (Pt-1 – Pt-3) were synthesized and characterized. Their photophysics, aggregation included emission (AIE) and optical power limiting properties were systematically investigated via UV−Vis absorption, emission, transient absorption, and nonlinear transmission spectroscopy/technique. These complexes exhibit 1π-π* transitions/metal-to-ligand charge transfer (1MLCT) absorption bands in UV-Vis spectral region and green fluorescence assigned to 1π-π* state mixed with 1MLCT character. All complexes exhibit obvious AIE in CH3CN-water solution system. When water fraction increased, nanoparticles of Pt(II) complexes were formed owing to the aggregation, and the emission intensity and triplet excited state lifetime both increased. In addition, complexes Pt-1 – Pt-3 all exhibit triplet transient absorption (TA) in visible region, where reverse saturable absorption (RSA) could occur. The strength of RSA at 532 nm follows the trend: Pt-2 > Pt-3 > Pt-1. The significant AIE, TA and OPL properties of these complexes would be useful for rational design of transition-metal complexes with high emission quantum yield, broadband excited-state absorption, long excited-state lifetime, and strong nonlinear absorption for multi-functional applications.Download high-res image (211KB)Download full-size image

A novel method was developed to produce 2-nitro-4-methylsulfonylbenzoic acid (NMSBA) from the oxidation of 2-nitro-4-methylsulfonyltoluene (NMST) by oxygen catalyzed by iron(II) phthalocyanine (FePc) and copper(II) phthalocyanine (CuPc). The order of activity for oxidation of NMST was found to be: FePc > CuPc. Meanwhile, major reaction parameters such as concentrations of catalyst and NaOH, reaction temperature and oxygen pressure have been investigated. Through optimization of the reaction parameters, the highest yield of NMSBA and conversion of NMST (up to 53%, 89.3%, respectively) were achieved with oxygen (2.0 MPa), FePc (\(1.0\times 10^{-4}\,\hbox {mol } \hbox {L}^{-1}\)), NaOH (\(0.6\,\hbox {mol } \hbox {L}^{-1}\)), in methanol at 55\(^{\circ }\hbox {C}\) for 8 h. A plausible mechanism for this catalytic process is proposed which involved deprotonation and radical pathways.

•Novel Fe(II) phthalocyanine modified SBA-15 heterogeneous catalysts were prepared.•Efficient catalytic performance for toluene aerobic oxidation.•The selectivity of product depends on the catalyst surface composition and porosity.•Catalyst recycled for three times without significant decrease in catalytic activity.Iron(II) tetracarboxyl phthalocyanine (tcFePc) grafted onto amino-functionalized SBA-15 catalysts for selective oxidation of toluene by oxygen and N-hydroxyphthalimide (NHPI) were studied under mild conditions. The catalysts were characterized by nitrogen adsorption measurements, X-ray diffraction, element analyses, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Their catalytic performance depended on the isolated amino group and tcFePc contents, which induced the surface composition and porosity of the catalysts. Less isolated amino groups (2.4 μmol/m2) and more grafted tcFePc (20 wt%) facilitate the oxidation efficiency of toluene to benzoic acid. Meanwhile, more isolated amino groups (3.8 μmol/m2) and less grafted tcFePc (11 wt%) weaken the oxidation activity of toluene and tend to form benzaldehyde. Reaction parameters, reaction scope and catalyst reusability were also investigated over 20 wt% tcFePc@NH2-SBA-15-3. Moreover, a plausible pathway for this catalytic process was proposed to involve a radical mechanism.Iron(II) tetracarboxyl phthalocyanine (tcFePc) immobilized onto amino-functionalized SBA-15 catalysts for selective oxidation of toluene by oxygen and N-hydroxyphthalimide (NHPI) were studied under mild conditions. It is found that the surface composition and porosity of these catalysts could tune the selectivity of products in toluene aerobic oxidation.Download high-res image (57KB)Download full-size image

•A 1,8-naphthalimide derivative (NI-1) has been designed and synthesized.•NI-1 qualifies strong AIE characteristic and can be encapsulated in SiO2 to form a nano-composite (NI-1@SiO2).•NI-1@SiO2 can go through cell membrane and specifically light up the mitochondria.•The energy-dependent cell uptake mechanism could responsible for the materials internalization.An organic fluorescent 1,8-naphthalimide derivative (NI-1) was designed and synthesized. Its photophysical properties were systematically investigated by a series of spectroscopic and theoretical methods. The twisted intramolecular charge transfer (TICT) was proved within NI-1 in various solutions. After adding H2O into its CH3CN solution, the aggregation induced emission (AIE) of NI-1 occurred, during which the enhanced green-yellow fluorescence and quantum yield up to 0.62 were monitored. In addition, SiO2 was used to coat on the surface of NI-1 to fabricate the composite nano structure (NI-1@SiO2). This nanomaterial not only qualifies AIE-active characteristic, but also exhibits remarkable anti-photobleaching ability and good biocompatibility. The NI-1@SiO2 can go through the cell membrane and specifically light up the mitochondria. The cellular uptake mechanism studies revealed that the energy-dependent cell uptake mechanism was responsible for the NI-1@SiO2 entering cells. The NI-1@SiO2 could be utilized as an efficient AIE-active fluorescent material and mitochondria imaging reagent.Download high-res image (226KB)Download full-size image

•A highly efficient green PHOLED was designed and fabricated.•Luminous efficiency of PHOLED has been greatly improved by using a double-host system.•The PHOLED exhibits a maximum external quantum efficiency of 19.05%.A highly efficient green phosphorescent organic light-emitting diode (PHOLED) was achieved from two co-evaporated materials, 2,4-diphenyl-6-bis(12-phenylindolo) [2,3-a]carbazole-11-yl)-1,3,5-triazine (DICT) and 9-phenyl-3,6-bis (9-phenylfluoren-9-yl)carbazole (PBFC), in the emitting layer. By utilizing DICT: PBFC = 1:1 as double-host combination and 12 wt% tris(2-phenylpyridine) iridium (Ir(ppy)3) as dopant, the PHOLED exhibits outstanding performance in terms of a maximum external quantum efficiency of 19.05%, a maximum current efficiency of 69.38 cd A−1 and a maximum power efficiency of 77.29 lm W−1, respectively. The device performance is significantly improved compared to those of the single-host material devices based on DICT (15.91%, 57.83 cd A−1 and 72.45 lm W−1) and PBFC (9.19%, 32.67 cd A−1 and 9.64 lm W−1). Furthermore, both host materials show relatively high glass transition temperatures (Tg) of 129.8 °C for DICT and 167.7 °C for PBFC, as well as excellent decomposition temperatures (Td) of 353.5 °C for DICT and 460.3 °C for PBFC respectively. The developed double-host system could be promising combination of host materials, especially for the application of high performance OLED and other organic electronic devices.Download high-res image (189KB)Download full-size image

Self-assembled fibrous films are expected to be an efficient approach for volatile organic amine (VOA) detection because of their fast response and high sensitivity and facile preparation of portable instruments. Herein, two D–π–A type salicylaldehyde derivatives functionalized naphthalimides (SFN) and tert-butyl carbazole (SFC) were synthesized, and their photophysical properties were investigated systematically. Both compounds display significant aggregation-induced emission behaviors originating from twisted intramolecular charge transfer (TICT) and restricted intramolecular rotation (RIR). Moreover, hydrogen bonding and π–π interactions with the assistance of dipole–dipole interactions enable the formation of self-assembled fibrous films from SFN and SFC, respectively. In particular, nanofibril-based films are introduced to detect VOA vapors with high performance through deprotonation and the Schiff base reaction. The fluorescence intensity of the films is quenched dramatically for SFN and enhanced significantly for SFC after exposure to the VOA vapors. These salicylaldehyde derivatives can be used for the design of efficient fluorescent chemosensors, and their self-assembled fibrous films are promising sensors for VOA detection.

Four heteroleptic cationic Ir(III) complexes [(X)2Ir(L2)]+PF6− were designed and synthesized, where L2 = 3,6-di-tert-butyl-9-(4-(4,5-dimethyl-2-(pyridin-2-yl)-1H-imidazol-1-yl)butyl)-9H-carbazole, X = difluorophenylpyridine (dfppy) (1), dimethylphenylpyridine (dmppy) (2), difluorophenylquinoline (dfpq) (3), dimethylphenylquinoline (dmpq) (4). Their photophysical properties have been systematically investigated via a series of spectroscopic methods. All complexes show fluorescence–phosphorescence dual-emission, aggregation-induced fluorescence emission (AIFE) and aggregation-induced phosphorescence emission (AIPE) in a solvent. Meanwhile, green to red emission colors are exhibited in the solid state. Noticeably, complex 2 shows evident piezochromic and vapochromic behaviors. The emission colors of complex 2 can be reversed from green to yellow upon grinding and CH2Cl2 fuming, which is further demonstrated using solid state and powder X-ray diffraction spectroscopy. Additionally, complex 2 is used in data security protection and provides a strategy to design smart luminescent materials.

•A series of terpyridyl Pt(II) complexes were synthesized and characterized.•The photophysics and nonlinear absorption of these complexes were investigated.•Three complexes exhibit RSA for the ns laser pulses at 532 nm.A series of 4-phenyl-2,2′; 6′,2″-terpyridyl Pt(II) complexes bearing different σ-alkynyl ancillary ligands (1a–1f) were synthesized and characterized. All complexes exhibit strong 1π,π* absorption bands in the UV region; and broad, structureless metal-to-ligand charge transfer (1MLCT)/ligand-to-ligand charge transfer (1LLCT) absorption bands in the visible region. When excited at the charge-transfer absorption band, the complexes exhibit yellow to red luminescence (λmax = 553–608 nm) in CH3CN at room temperature, which is attributed to the 3MLCT/3LLCT state, except 1c. The emitting state of 1c exhibits a significant intraligand 3π,π* character, which is originated from the naphthalimide acetylide ligand. Complexes 1a–1c exhibit moderate triplet transient absorptions from visible to NIR region, where reverse saturable absorption (RSA) occurs. The photophysical, electrochemical and nonlinear absorption properties of these Pt(II) complexes can be tuned drastically by the different acetylide ligand, which would be useful for rational design of broadband nonlinear absorption materials.A series of 4-phenyl-2,2′; 6′,2″-terpyridyl Pt(II) complexes bearing different σ-alkynyl ancillary ligands (1a–1f) were synthesized and characterized. Their photophysical, electrochemical and nonlinear absorption properties can be tuned drastically by the acetylide ligand, which would be useful for rational design of transition-metal complexes for organic light-emitting materials and broadband nonlinear absorption materials.

Two aza-boron-diquinomethene (aza-BODIQU) complexes bearing phenyl and carbazyl substituents were synthesized and characterized. Their photophysical properties were investigated systematically via spectroscopic and theoretical methods. Both complexes exhibit strong 1π-π* transition absorptions (λabs = 400–540 nm) and intense fluorescent emissions (λem = 440–600 nm, ΦPL = 0.93 and 0.78) in CH2Cl2 solution and in solid state at room temperature. Compared to the complex with phenyl groups, the complex bearing carbazyl groups shows significant bathochromic shift in both absorption and emission. This could be attributed to the larger π-electron conjugation of the carbazole unit and intramolecular charge transfer feature from carbazole to aza-BODIQU component. In addition, the complexes exhibit intense photoluminescence and good stability on antacid, anti-alkali and stability in printing ink samples, which makes them potential dopants for the application of fluorescent security inks.

A series of β-diketone derivatives bearing tetraphenylene (TPE) moieties were synthesized and characterized. Their photophysical properties were investigated systematically via spectroscopic and theoretical methods. All compounds exhibit broad absorption bands between 300 and 450 nm, which are assigned to the 1π-π* transition of the conjugated system mixed intramolecular charge-transfer (ICT) transitions. Meanwhile, the emission of these compounds in solution at room temperature (λem = 458 ~ 509 nm) can be attributed to the 1π,π*/1ICT state. Introduction of freely rotatable TPE to conventional β-diketone luminophors quenches their light emissions in the solutions, but endows these molecules with aggregation-induced emission (AIE) characteristics in the condensed phase due to the restriction of intramolecular rotation. The spectroscopic studies and theoretical calculations indicate that the photophysical properties of these β-diketone derivatives can be tuned by the appended substituents, which would be useful for rational design of AIE compounds with high solid state luminescence performance. Furthermore, these AIE-active compounds exhibited distinct piezofluorochromic properties and switched reversibly upon grinding-fuming. Their photophysical properties have been investigated with the aim to provide a basis for elucidating the structure-property correlations and developing new multi-stimuli responsive luminescent materials.

A series of aza-boron-diquinomethene complexes (1a–1e) bearing different N-aryl chromophores were synthesized and characterized by multinuclear NMR spectroscopy, X-ray crystallography, optical absorption and emission spectroscopy, and elemental analysis. These robust thermal complexes possess tunable intense luminescence from blue to red with relatively high emission quantum yields. The introduction of different N-aryl chromophores into the aza-BODIQU core significantly tuned the emission colors. The relationship between their structures and properties was investigated systematically via spectroscopic methods and simulated by density functional theory (DFT) calculations. Additionally, the application of 1c as a pH sensor with a remarkable colour-changing property has been investigated. All these results indicate that these complexes exhibit robust thermal stability, tunable photophysical properties, relatively high photoluminescence quantum yields and protonation effect, making these complexes potential candidates for pH sensors, bioimaging probes and organic light-emitting materials.

•A hole transporting material was synthesized and characterized.•The compound exhibits high hole mobility and excellent thermal stability.•The resulting device exhibits higher efficiency compared with NPB-device.A hole-transporting material, N1,N1,N3,N3-tetra([1,1′-biphenyl]-4-yl)-N5,N5-diphenylbenzene-1,3,5-triamine (TDAB-BP), was synthesized by di([1,1′-biphenyl]-4-yl)amine and 3,5-dichloro-N,N-diphenylaniline via Buchwald–Hartwig coupling reaction. The material exhibit high hole mobility, excellent thermal and morphological stability. TDAB-based OLED device exhibited the highest performance in terms of the maximum current efficiency (9.34 cd/A), maximum power efficiency (5.89 lm/W), and maximum external quantum efficiency (6.61%), which is significantly improved than that of the standard device based on 4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]-biphenyl (NPB) (7.12 cd/A, 4.90 lm/W and 5.31%). Furthermore, TDAB-BP shows a higher decomposition temperature (Td) of 505 °C than that of NPB (418 °C). This material could be a promising hole-transporting material, especially for the high-temperature applications of OLEDs and other organic electronic devices.A hole-transporting material TDAB-BP was synthesized, which exhibits high hole mobility, excellent thermal and morphological stability. Blue OLED device based on TDAB-BP exhibits high performance with the maximum current efficiency of 9.34 cd/A, maximum power efficiency of 5.89 lm/W and maximum external quantum efficiency of 6.61%. TDAB-BP could significantly improve the device performance than traditional NPB.

Two polycyclic aromatic hydrocarbons bearing trimethylsilylethynyl groups were designed and synthesized as new colorimetric and ratiometric fluorescent probes for fluoride anion. Both probes exhibit high specific selectivity and sensitivity for F− compared to other anions. When F− is added to the solution of the probe, the trimethylsilyl substituents can be removed immediately, and the color of the solution changes from yellow to colorless under ambient light. Moreover, test papers based on the probes are prepared, which could be applied to detect F− in organic phase.

A novel AIE-active boron-difluoride complex (PTZ) was synthesized which exhibits multi-stimuli responsive characteristics. Its colours and emissions can be switched by mechanical grinding, organic solvent vapours and acid/base vapours. This complex can be utilized in data encryption and decryption based on the protonation–deprotonation effect.

A series of aza-boron-diquinomethene complexes (1a–1e) bearing different N-aryl chromophores were synthesized and characterized by multinuclear NMR spectroscopy, X-ray crystallography, optical absorption and emission spectroscopy, and elemental analysis. These robust thermal complexes possess tunable intense luminescence from blue to red with relatively high emission quantum yields. The introduction of different N-aryl chromophores into the aza-BODIQU core significantly tuned the emission colors. The relationship between their structures and properties was investigated systematically via spectroscopic methods and simulated by density functional theory (DFT) calculations. Additionally, the application of 1c as a pH sensor with a remarkable colour-changing property has been investigated. All these results indicate that these complexes exhibit robust thermal stability, tunable photophysical properties, relatively high photoluminescence quantum yields and protonation effect, making these complexes potential candidates for pH sensors, bioimaging probes and organic light-emitting materials.

A novel AIE-active boron-difluoride complex (PTZ) was synthesized which exhibits multi-stimuli responsive characteristics. Its colours and emissions can be switched by mechanical grinding, organic solvent vapours and acid/base vapours. This complex can be utilized in data encryption and decryption based on the protonation–deprotonation effect.

Four heteroleptic cationic Ir(III) complexes [(X)2Ir(L2)]+PF6− were designed and synthesized, where L2 = 3,6-di-tert-butyl-9-(4-(4,5-dimethyl-2-(pyridin-2-yl)-1H-imidazol-1-yl)butyl)-9H-carbazole, X = difluorophenylpyridine (dfppy) (1), dimethylphenylpyridine (dmppy) (2), difluorophenylquinoline (dfpq) (3), dimethylphenylquinoline (dmpq) (4). Their photophysical properties have been systematically investigated via a series of spectroscopic methods. All complexes show fluorescence–phosphorescence dual-emission, aggregation-induced fluorescence emission (AIFE) and aggregation-induced phosphorescence emission (AIPE) in a solvent. Meanwhile, green to red emission colors are exhibited in the solid state. Noticeably, complex 2 shows evident piezochromic and vapochromic behaviors. The emission colors of complex 2 can be reversed from green to yellow upon grinding and CH2Cl2 fuming, which is further demonstrated using solid state and powder X-ray diffraction spectroscopy. Additionally, complex 2 is used in data security protection and provides a strategy to design smart luminescent materials.