A fluorescent sensor array based on a single cucurbit[5]uril-truxene probe for simultaneous identification of five heavy metal ions

There is a need to develop simple and effective strategies for the rapid detection of heavy metal ions (HMIs) in order to protect the environment and human health. A simple fluorescent sensor array based on a single cucurbit[5]uril-truxene probe was proposed to simultaneously identify five HMIs (Pb2+, Cu2+, Ag+, Fe2+ and Fe3+). This probe was synthesized using monohydroxyl cucurbit[5]uril and monobromohexyl truxene by a substitution reaction between them. It could be observed that the fluorescence response of this synthesized probe to HMIs was closely related to the pH of the aqueous solution, exhibiting different fluorescence intensities at pH 3.0, 7.0, and 9.0. Based on this phenomenon, a fluorescent sensor array based on a single cucurbit[5]uril-truxene probe was then constructed by simply altering the pH in the sensor element. These unique fluorescence responses were analyzed using linear discriminant analysis (LDA) to identify metal ions. A concentration limit classification of 0.1 μM was applied to the above five HMIs. Moreover, the quantification of metal ions was implemented even at low concentrations of 48-121 nM. This array showed good results in the recognition of metal ions in real water samples (lake water and tap water samples), which shows its broad application prospects in many fields, including monitoring of the environmental water quality and so on.

Tetracyanobutadiene Bridged Push-Pull Chromophores: Development of New Generation Optoelectronic Materials

This review describes the design strategies used for the synthesis of various tetracyanobutadiene bridged donor-acceptor molecular architectures by a click type [2+2] cycloaddition-retroelectrocyclization (CA-RE) reaction sequence. The photophysical and electrochemical properties of the tetracyanobutadiene bridged molecular architectures based on various moieties including diketopyrrolopyrrole, isoindigo, benzothiadiazole, pyrene, pyrazabole, truxene, boron dipyrromethene (BODIPY), phenothiazine, triphenylamine, thiazole and bisthiazole are summarized. Further, we discuss some important applications of the tetracyanobutadiene bridged derivatives in dye sensitized solar cells, bulk heterojunction solar cells and photothermal cancer therapy.

P2O5-Promoted Cyclization of Di[aryl(hetaryl)methyl] Malonic Acids as a Pathway to Fused Spiro[4.4]nonane-1,6-Diones

Conventional spiro-linked conjugated materials are attractive for organic optoelectronic applications due to the unique combination of their optical and electronic properties. However, spiro-linked conjugated materials with conjugation extension directed along the main axis of the molecule are still only rare examples among the vast number of spiro-linked conjugated materials. Herein, the synthesis, leading to π-extended spiro-linked conjugated materials─spiro[4.4]nonane-1,6-diones and spiro[5.5]undecane-1,7-diones─has been developed and optimized. The proposed design concept starts from readily available malonic esters and contains several steps: double alkylation of malonic ester with bromomethylaryl(hetaryl)s; conversion of a malonic ester into the corresponding malonic acid; electrophilic spirocyclization of the latter into the annulated spiro[4.4]nonane-1,6-dione or spiro[5.5]undecane-1,7-dione in the presence of phosphorus pentoxide. On the basis of these insights, the developed method yielded spiro-linked conjugated cores fused with benzene, thiophene, and naphthalene, decorated with active halogen atoms. The structures of the synthesized spirocycles were determined by single-crystal X-ray diffraction analysis. Benzene fused spiro[4.4]nonane-1,6-dione decorated with bromine atoms was transformed into V-shape phenylene-thiophene co-oligomer type spirodimers via Stille coupling. The spiro-bis(4-n-dodecylphenyl)-2,2'-bithiophene derivative possessed high photoluminescence properties in both solution and solid state with a photoluminescence quantum yield (PL QY) of 38%.

From truxenes to heterotruxenes: playing with heteroatoms and the symmetry of molecules

As a result of the modification of truxene, we can change the electronic structure or create multidimensional materials. Thus, the use of truxenes is very wide.

Near infrared absorption/emission perylenebisimide fluorophores with geometry relaxation-induced large Stokes shift

The dyes (P-1 and P-2) of perylenebisimide (PBI) conjugated with 2-(2-hydroxyphenyl)benzothiazole (HBT) were prepared by Sonogashira coupling reaction. The new compounds have special photophysical properties, such as near infrared absorption/emission and large Stokes shift. The UV-vis absorption (range from 651 nm to 690 nm) and emission wavelength (range from 732 nm to 756 nm) of P-1 and P-2 extend to near infrared range. Importantly, they have much larger Stokes shifts (range from 73 nm to 105 nm) compared with the conventional PBI derivatives, such as 7 (from 19 nm to 65 nm) and 9 (from 81 nm to 86 nm). TD-DFT calculation was used to rationalize UV-vis absorption, emission and especially large Stokes shift from the theoretical point of view. We found geometry relaxation of P-1 and P-2 in the excited state is an important reason for the origin of large Stokes shift besides intramolecular electron transfer (ICT).

The dyes with near infrared absorption/emission and large stokes shifts induced by geometry relaxation were prepared.

Perylene diimides: will they flourish as reaction-based probes?

Perylene diimides (PDI) are a well-studied class of functional organic dyes, and in recent years, they have been accepted as promising scaffolds for the design of small molecule/polymer-based chromogenic and fluorogenic reaction-based-probes because of their strong absorption combined with high fluorescence quantum yield in organic solvents, low reduction potential, good electron-acceptor properties, and broad color range properties. Undoubtedly, the intrinsically poor solubility of PDI-based derivatives in water greatly hampers their exploitation as reaction-based probes; however, a vast array of functionalizations now offer design strategies that have resulted in >50% solubility of PDI derivatives in water. A chemodosimeter, wherein chemical transformation is achieved by specific reactions, affords naked-eye visibility, fast response time, sensitivity, ratiometric response, and low cost. The present review focuses on the progress of PDI-based chemodosimeters achieved so far since the inception of this member in the rylene diimide family. This comprehensive review may facilitate the development of more powerful chemodosimeters based on PDI for broad and exciting applications in the future.

C3-Symmetric star shaped donor–acceptor truxenes: synthesis and photophysical, electrochemical and computational studies

This manuscript reports the design and synthesis of C₃-symmetric star shaped donor and acceptor substituted truxenes 6, 7, 10 and 11 using Pd-catalyzed Sonogashira cross-coupling and [2+2] cycloaddition–retroelectrocyclization reactions.

Carbocyclization approaches to electron-deficient nanographenes and their analogues

Versatile π-aromatic building blocks and selective coupling transformations enable rapid assembly of complex electron-deficient molecules, useful as n-type organic semiconductors.

Understanding Electron Transport in Disk-Shaped Triphenylene-Tris(naphthaleneimidazole)s through Structural Modification and Theoretical Investigation

Disk-shaped molecules with large aromatic π-surfaces are a class of organic semiconductors in which the charge-carrier transport properties could be greatly facilitated by preferred intermolecular stacking of the π-surfaces. The optical and electronic properties are not only determined by the core aromatic structure of these disk-shaped molecules but are also strongly dependent on the side chains, which directly impact the molecular self-assembly behavior in condensed phases. Triphenylene-tris(naphthaleneimidazole) (TP-TNI) is a recently reported n-type semiconductor featuring a large π-core and branched side chains, with an electron-transporting mobility reaching 10^-4 cm² V^-1 s^-1. To further improve material performance, a detailed study is needed to understand the dependence of carrier transport properties on both the core electronic structure and side chain. Here, we present the detailed synthesis and characterization of a TP-TNI derivative bearing linear side chains, which has demonstrated a field-effect electron-transport mobility of up to 1.3 × 10^-3 cm² V^-1 s^-1. The more than 1 order improvement in electron-transport properties over the branched side chain homologue can be correlated to ordered twisted packing in the thin film, as revealed by in situ variable temperature grazing incidence wide-angle X-ray scattering studies. In-depth theoretical understanding of the frontier orbitals, reorganization energies, and charge-transfer integrals of TP-TNI molecules has provided further insight into the relationship between the molecular stacking geometry and charge-transport properties.

Rearrangement of an aniline linked perylene bisimide under acidic conditions and visible to near-infrared emission from the intramolecular charge-transfer state of its fused derivatives

We have prepared a series of aniline-linked and fused perylene bisimides (PBIs) for making near-infrared (NIR) fluorophores. During this research, we found an unexpected rearrangement reaction on the PBI core for the first time. The aniline- and phenothiazine-fused PBIs exhibit excellent absorption ability and visible-to-NIR emission owing to their intramolecular charge transfer character.

Lighting the Way to See Inside Two-Photon Absorption Materials: Structure-Property Relationship and Biological Imaging

The application of two-photon absorption (2PA) materials is a classical research field and has recently attracted increasing interest. It has generated a demand for new dyes with high 2PA cross-sections. In this short review, we briefly cover the structure-2PA property relationships of organic fluorophores, organic-inorganic nanohybrids and metal complexes explored by our group. (1) The two-photon absorption cross-section (δ) of organic fluorophores increases with the extent of charge transfer, which is important to optimize the core, donor-acceptor pair, and conjugation-bridge to obtain a large δ value. Among the various cores, triphenylamine appears to be an efficient core. Lengthening of the conjugation with styryl groups in the D-π-D quadrupoles and D-π-A dipoles increased δ over a long wavelength range than when vinylene groups were used. Large values of δ were observed for extended conjugation length and moderate donor-acceptors in the near-IR wavelengths. The δ value of the three-arm octupole is larger than that of the individual arm, if the core has electron accepting groups that allow significant electronic coupling between the arms; (2) Optical functional organic/inorganic hybrid materials usually show high thermal stability and excellent optical activity; therefore the design of functional organic molecules to build functional organic-inorganic hybrids and optimize the 2PA properties are significant. Advances have been made in the design of organic-inorganic nanohybrid materials of different sizes and shapes for 2PA property, which provide useful examples to illustrate the new features of the 2PA response in comparison to the more thoroughly investigated donor-acceptor based organic compounds and inorganic components; (3) Metal complexes are of particular interest for the design of new materials with large 2PA ability. They offer a wide range of metals with different ligands, which can give rise to tunable electronic and 2PA properties. The metal ions, including transition metals and lanthanides, can serve as an important part of the structure to control the intramolecular charge-transfer process that drives the 2PA process. As templates, transition metal ions can assemble simple to more sophisticated ligands in a variety of multipolar arrangements resulting in interesting and tailorable electronic and optical properties, depending on the nature of the metal center and the energetics of the metal-ligand interactions, such as intraligand charge-transfer (ILCT) and metal-ligand charge-transfer (MLCT) processes. Lanthanide complexes are attractive for a number of reasons: (i) their visible emissions are quite long-lived; (ii) their absorption and emission can be tuned with the aid of appropriate photoactive ligands; (iii) the accessible energy-transfer path between the photo-active ligands and the lanthanide ion can facilitate efficient lanthanide-based 2PA properties. Thus, the above materials with excellent 2PA properties should be applied in two-photon applications, especially two-photon fluorescence microscopy (TPFM) and related emission-based applications. Furthermore, the progress of research into the use of those new 2PA materials with moderate 2PA cross section in the near-infrared region, good Materials 2017, 10, 223 2 of 37 biocompatibility, and enhanced two-photon excited fluorescence for two-photon bio-imaging is summarized. In addition, several possible future directions in this field are also discussed (146 references).

Monothiatruxene: a new versatile core for functional materials

A monothiatruxene and its oxidized and/or brominated derivatives were prepared through an efficient route.

Synthesis of a Crushed Fullerene C60H24 through Sixfold Palladium-Catalyzed Arylation

The synthesis of a new C3v -symmetric crushed fullerene C60H24 (5) has been accomplished in three steps from truxene through sixfold palladium-catalyzed intramolecular arylation of a syn-trialkylated truxene precursor. Laser irradiation of 5 induces cyclodehydrogenation processes that result in the formation of C60, as detected by LDI-MS.

Coronene-Containing N-Heteroarenes: 13 Rings in a Row

We describe the modular synthesis of three novel large N-heteroarenes, containing 9, 11, and 13 annulated rings. This modular system features fused azaacene units to a coronene nucleus. We evaluate the optical and electronic properties and the solid-state packing of the targets. The electronic properties of the 13-ring N-heteroarene allow the fabrication of a proof-of-concept thin-film transistor. Electron mobilities up to 8 × 10(-4) cm/(V s) were obtained for polycrystalline films.

Design, synthesis, linear and nonlinear photophysical properties of novel pyrimidine-based imidazole derivatives

Novel pyrimidine imidazole derivatives with flexible ether chains have been synthesised and evaluated for their cell imaging performanceviaphotophysical investigations and theoretical calculations.

Synthesis and use of “clickable” bay-region tetrasubstituted perylene tetracarboxylic tetraesters and a perylene monoimide diester as energy acceptors

Novel perylene derivatives are ready to be used as functional energy acceptors in light-harvesting systems.

Truxene: a promising scaffold for future materials

Truxene (10,15-dihydro-5H-diindeno[1,2-a;1′,2′-c]fluorene), which is a heptacyclic polyarene structure, has attracted a great deal of interest due to its exceptional solubility, high thermal stability and ease with which it may be modified.

A soluble ladder-conjugated star-shaped oligomer composed of four perylene diimide branches and a fluorene core: synthesis and properties

A new ladder-conjugated star-shaped oligomer electron-transporting material TetraPDI-PF, with four perylene diimide (PDI) branches and a fluorene core, was efficiently synthesized. The oligomer is highly soluble in dichlorobenzene with a solubility of 155 mg mL(-1), which is higher than those of PDI (35 mg mL(-1)) and PDI-Phen (70 mg mL(-1)). Demonstrated by thermogravimetric analysis (TGA), the oligomer exhibits excellent thermal stability with the decomposition temperature (Td) of 291.2 °C, which is 65 °C higher than that of PDI. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to investigate the electrochemical properties. Although the CV curves of TetraPDI-PF are successively scanned for 15 cycles, they still remain invariable reduction potentials. The oligomer also shows outstanding photostability, even better than PDI, which maintains 99 % fluorescence intensity after irradiation for 10 min using maximum laser intensity. In the steady-state space-charge-limited current (SCLC) devices, TetraPDI-PF exhibits higher intrinsic electron mobility of 2.22×10(-5) cm(2)  V(-1)  s(-1), three orders of magnitude over that of PDI (3.52×10(-8) cm(2)  V(-1)  s(-1)). The bulk heterojunction (BHJ) organic solar cells (OSCs) using TetraPDI-PF as non-fullerene acceptors and P3HT as donors give optimum power conversion efficiency (PCE) of 0.64 %, which is 64 times that of the PDI:P3HT BHJ cells.

Synthesis and crystal structure of a novel copper(ii) complex of curcumin-type and its application in in vitro and in vivo imaging

The results of TPEF imaging in a tumor-bearing mouse model demonstrated the potential of the obtained complex for in vivo tumor diagnosis.