Perfluoro-tert-butyl Group-Derived Capmatinib: Synthesis, Biological Evaluation and Its Application in 19 F Magnetic Resonance Imaging.

Capmatinib is an FDA-approved drug to treat metastatic non-small cell lung cancer with MET-exon 14 skipping. Herein, the perfluoro-tert-butyl group, which possesses nine chemically identical fluorine atoms, was introduced on Capmatinib to afford a targeted 19 F magnetic resonance imaging (MRI) probe, perfluoro-tert-butyl group-derived Capmatinib (9F-CAP). The 19 F MRI concentration limit was found to be 25 mM in FLASH sequence. Molecular docking simulation, surface plasmon resonance (SPR) (with a Kd of 40.7 µM), half-inhibitory concentration (with a IC50 of 168 nM), Annexin V, and cytotoxicity assays jointly demonstrated that the 9F-CAP targeted cMET protein specifically. Therefore, the targeted imaging capability of 9F-CAP is of great significance for the preoperative diagnosis of specific cancers.

Synthesis, Structure, and Properties of Monodispersed and Highly Luminescent Organoborane Oligomers.

Organoborane oligomers with well-defined molecular structures and high luminescence are scarce, among which those with boron not used as bridging atoms are even more so. Here, a series of well-defined ethynyl-linked or butadiynyl-linked conjugated organoborane oligomers with high fluorescence quantum yield and extinction coefficient (i.e., high brightness) were prepared by coupling different building blocks featuring dithienooxadiborepine moieties. Single crystal structures of hexyl modified dithienooxadiborepine (1a-hex) and hexyl-modified butadiynyl-linked conjugated dimer (D2-hex) not only verified the identity of the molecular structures but also revealed that the introduction of the hexyl chains distorted the molecular structures due to steric hindrance. Optical measurements showed that the absorption and emission maxima of the six oligomeric molecules bathochromic shifted with increasing numbers of repeating units. Molecules without hexyl chains emit efficient fluorescence upon photoexcitation, and the fluorescence quantum efficiency of the ethynyl-linked conjugated dimer (D1) is close to unity. Theoretical calculation results using density functional theory methods are consistent with the single crystal data, allowing a better understanding of the spectral properties. Such results indicate that the method is efficient for expanding small organoborane molecules into π-conjugated oligomers, which can be used to modulate to emit different colors with high efficiency.

Concurrent Cooperative J-Aggregates and Anticooperative H-Aggregates.

Completely understanding the working mechanisms of sophisticated supramolecular self-assembly exhibiting competing paths is very important for chemists en route to acquiring the ability of constructing supramolecular systems with controlled structures and designed functions. Here, the self-aggregation behaviors of an N-heterocyclic aromatic dicarboximide molecule 1, boasting two competing paths that give rise to different supramolecular structures and exhibit distinct thermodynamic features, are carefully examined. First, a group of H-aggregates are observed when providing a medium driving force for aromatic stacking, and their formation is manifested as an anticooperative process. When exposed to enhanced strength of aromatic interactions, these H-aggregates are found to transform into J-aggregates via a cooperative assembly mechanism. With the assistance of a mathematic model accommodating two competing polymerization pathways, calculations are conducted to simulate and explain the thermodynamic equilibria of such a unique supramolecular system. The calculation results are highly consistent with the experimental observations, and some important properties are elucidated. Specifically, the anticooperative assembly mechanism generally promotes the formation of low to medium oligomers, whereas the cooperative path is more competent at producing high polymers. If the anticooperative and cooperative routes coexist and compete for the same molecule, the cooperative formations of high polymers are significantly suppressed unless a very high degree of polymerization can be achieved. Such a unique feature of concurring anticooperative and cooperative paths emerges to the H- and J-aggregates of molecule 1 and thus brings about the interesting sequential appearances of the two types of aggregates under conditions of continuously enlarged driving force for self-aggregation. Finally, based on the knowledge acquired from this study and by analyzing the steric features of 1 that influence its supramolecular packing motifs, a slightly modified molecular structure is designed, with which the intermediate H-aggregation state was successfully suppressed, and a single cooperative J-aggregation path is manifested.

An Air-Stable Organoboron Compound, Dithienooxadiborepine: Preparation and Functionalization.

π-Conjugated organoboron molecules, which are easy to prepare, stable against moisture, and easy to functionalize, are scarce. Here, we report a one-pot synthesis of an air-stable organoboron compound, dithienooxadiborepine 1 in 17% yield on a 600 mg scale without separation or handling an air-sensitive intermediate. Dithienooxadiborepine 1 showed excellent stability under ambient conditions, allowing conventional column chromatography purification. Functionalization of 1 was realized via direct bromination using NBS and further Stille coupling reactions, giving access to longer π-conjugated molecules 5A and 5B. Single-crystal structures of compounds 4, 5A, and 5B not only unambiguously verified the chemical identity of dithienooxadiborepine 1 but also revealed that both the seven-member oxadiborepine ring and the 5-7-5 fused dithienooxadiborepine ring system are planar. UV-vis absorption and fluorescence emission measurements of 5A and 5B showed bathochromic shifted absorption and emission relative to 1, evidencing good π-conjugation. Cyclic voltammograms of 5A and 5B displayed two reduction peaks corresponding to two electron-accepting events at two boron atoms. These results proved dithienooxadiborepine 1 a potent π-conjugating building block for electron-accepting materials.

Three-Dimensionally Homoconjugated Carbon-Bridged Oligophenylenevinylene for Perovskite Solar Cells.

Stabilization of the radical cationic state of a donor molecule by 3-D homoconjugation was probed using a substituted carbon-bridged oligophenylenevinylene backbone (COPV, or 5,5-diarylindeno[2,1-a]indenes). For molecules bearing electron-donating groups as the 5,5-aryl moieties, a one-electron oxidation of the COPV backbone results in delocalization of the cationic charge over the whole molecule with a small reorganization energy. The compounds forming a stable radical cation by 3-D homoconjugation produce a uniform amorphous film and show high short-circuit current, high fill factor, and hence high power-conversion efficiency when used as a hole-transporting layer of an organic-inorganic hybrid lead perovskite solar cell. This material thus shows a performance and stability in air comparable to those obtained with the benchmark material, spiro-MeOTAD.

Supramolecular aggregates with distinct optical properties from PDI oligomers of similar structures.

The self-assembly behaviors of two series of monodispersed oligomers consisting of perylenediimide (PDI) linked by ethynylene and butadiynylene spacers are investigated in solutions. In spite of the very similar chemical structures, the two sets of oligomers manifest completely different optical properties upon self-aggregation, implying differed aggregate structures. While the oligomers containing butadiynylene spacers form H-aggregates, those featuring ethynylene linkers display J-aggregation characteristics. Thermodynamic analysis revealed that the self-association constants of both series of oligomers increase with the number of PDI units in the backbones. Oligomers containing the same number of PDI units but different spacers display nearly identical enthalpy changes. According to the molecular exciton theory, the observed H- and J-aggregates are suggested to comprise similar packing motifs with slightly varied slipping angles, giving rise to greatly disparate optical properties.

Planarization, fusion, and strain of carbon-bridged phenylenevinylene oligomers enhance π-electron and charge conjugation: a dissectional vibrational Raman study.

We have used Raman spectroscopy to study the molecular and electronic structures of the radical cations and dications of carbon-bridged oligo(para-phenylenevinylene)s (COPVn, n = 1-6) possessing consecutive fused pentagons and hexagons, up to 19, along with COPV derivatives having electron-donating and -withdrawing groups. This study was made possible by the outstanding stability of the charged states of COPVs. We could untangle the effects of π-conjugation in the planar structure on the Raman frequency by distinguishing it from other structural effects, such as strain in the vinylene groups shared by the two pentagons. The analyses showed that the radical cations have benzo-quinoidal structures confined in the center of the molecule, as well as benzo-aromatic rings at the terminal sites. In contrast, dications of COPVn longer than n = 3 exhibit a biradicaloid character because of the recovery of aromaticity in the central rings and quinoidal rings at the terminal positions. These biradicaloids favor a singlet nature in their ground electronic states because of the double spin polarization. The introduction of electron-donating and -withdrawing groups on the termini of a COPV core affords, upon oxidation or reduction, a fully delocalized class III mixed valence system because of the high degree of conjugation of the COPV platform, which favors extensive charge delocalization.

Chemical designs of functional photoactive molecular assemblies.

Molecular assemblies with well-defined structures capable of photo-induced electron transfer and charge transport or photochemical reactions are reviewed. Hierarchical supramolecular architectures, which assemble the modular units into specific spatial arrangements and facilitate them to work cooperatively, are vital for the achievement of photo-functions in these systems. The chemical design of molecular building blocks and noncovalent interactions exploited to realize supramolecular organizations are particularly discussed. Reviewing and recapitulating the chemical evolution traces of these accomplished systems will hopefully delineate certain fundamental design principles and guidelines useful for developing more advanced functions in the future.

Oligo(p-phenylene-ethynylene)s with backbone conformation controlled by competitive intramolecular hydrogen bonds.

A series of conjugated oligo(p-phenylene-ethynylene) (OPE) molecules with backbone conformations (that is, the relative orientations of the contained phenylene units) controlled by competitive intramolecular hydrogen bonds to be either co-planar or random were synthesised and studied. In these oligomers, carboxylate and amido substituents were attached to alternate phenylene units in the OPE backbone. These functional groups were able to form intramolecular hydrogen bonds between neighbouring phenylene units. Thereby, all phenylene units in the backbone were confined in a co-planar conformation. This planarised structure featured a more extended effective conjugation length than that of regular OPEs with phenylene units adopting random orientation due to a low rotational-energy barrier. However, if a tri(ethylene glycol) (Tg) side chain was appended to the amido group, it enabled another type of intramolecular hydrogen bond, formed by the Tg chain folding back and the contained ether oxygen atom competing with the ester carbonyl group as the hydrogen-bond acceptor. The outcome of this competition was proven to depend on the length of the alkylene linker joining the ether oxygen atom to the amido group. Specifically, if the Tg chain folded back to form a five-membered cyclic structure, this hydrogen-bonding motif was sufficiently robust to overrule the hydrogen bonds between adjacent phenylene units. Consequently, the oligomers assumed non-planar conformations. However, if the side chain formed a six-membered ring by hydrogen bonding with the amido NH group, such a motif was much less stable and yielded in the competition with the ester carbonyl group from the adjacent phenylene unit. Thus, the hydrogen bonds between the phenylene units remained, and the co-planar conformation was manifested. In our system, the hydrogen bonds formed by the back-folded Tg chain and amido NH group relied on a single oxygen atom as the hydrogen-bond acceptor. The additional oxygen atoms in the Tg chain made a negligible contribution. A bifurcated hydrogen-bond motif was unimportant. From our results, in combination with the results from an independent study by Meijer et al., it is evident that intramolecular hydrogen bonds involving back-folded oligo(ethylene glycol) moieties may differ in their structural details. Absorption spectroscopy served as a convenient yet sensitive technique for analysing hydrogen-bonding motifs in our study.

A foldamer at the liquid/graphite interface: the effect of interfacial interactions, solvent, concentration, and temperature.

The unfolding process and self-assembly of a foldable oligomer (foldamer 1) at the liquid/graphite interface were investigated by scanning tunnelling microscopy. At the level of molecular conformation, we identified several molecular conformations (A(z), B, C, D, E) that represent intermediate states during unfolding, which may help to elucidate the unfolding process at the liquid/graphite interface. Adsorption at the interface traps the intermediate states of the unfolding process, and STM has proved to be a powerful technique for investigating folding and unfolding of a foldamer at the molecular level, which are not accessible by other methods. The STM observations also revealed that varying the solvent and/or concentration results in different self-assemblies of foldamer 1 as a result of variations in molecular conformations. The solvent and concentration effects were attributed to the changes in existing states (extended or folded) of foldamers in solution, which in turn affect the distribution of adsorbed molecular conformations at the interface. This mechanism is quite different from other systems in which solvent and concentration effects were also observed.

White Light Luminescence from a Homo-conjugated Molecule with Thermally Activated Delayed Fluorescence.

Luminophores with tunable emission properties are appealing due to various applications. Among those properties, thermally activated delayed fluorescence (TADF) has been attracting enormous research interests. Herein, we synthesized a 9,9'-spirobifluorene based homo-conjugated molecule 1, which connects a diphenylamino moiety as electron donor and a naphthalimide group as electron acceptor via 2,2'-positions of spirofluorene. Compound 1 displays dual emission behaviour with both blue and orange fluorescence. The one orange fluorescence around 555 nmshows sensitivity to oxygen and a prolonged lifetime of 284 ns in degassed toluene. Such characteristics imply TADF nature for this emission from a charge-transfer excited state. The other emission at 440 nm with blue colour displayed resistance to oxygen quenching and a normal fluorescence lifetime of 1.5 ns. Compared with control molecule, this emission band is assigned as conventional fluorescence from a localized excited state. In addition, dual emission property allows molecule 1 to be modulated to emit white photoluminescence in thin film with a CIE color coordinate of (0.25, 0.33).

Light-Absorbing Pyridine Derivative as a New Electrolyte Additive for Developing Efficient Porphyrin Dye-Sensitized Solar Cells.

To fabricate efficient dye-sensitized solar cells (DSSCs), 4-tert-butylpyridine (TBP) is commonly used as an additive in the electrolytes for improving the photovoltages (VOC). However, TBP cannot play a positive role in improving the photocurrent (JSC) because of the lack of absorption in the visible-wavelength range. We herein report a light-absorbing pyridine derivative N1 as an additive for the axial coordination with porphyrin dyes. N1 was synthesized by introducing a (bis(4-methoxyphenyl)amino)anthryl moiety into the para-position of pyridine via an acetylene bridge, and porphyrin dye XW64 containing meso-3,5-disubstituted phenyl groups was synthesized considering that the meta-substituted phenyl groups may induce weaker steric hindrance with the axial pyridyl ligand, as compared with wrapped and strapped porphyrin dyes. Thus, N1 was used as an electrolyte additive together with TBP. When optimized concentrations of 6 mM N1 and 0.5 M TBP were used for fabricating DSSCs based on XW64, enhanced photovoltaic performance was achieved, with JSC, VOC, and efficiency of 15.65 mA·cm-2, 0.701 V, and 7.35%, respectively, superior to those of the corresponding DSSCs without using the additives (JSC = 14.86 mA·cm-2, VOC = 0.599 V, and efficiency = 5.94%). The enhancement of JSC can be ascribed to the improved light-harvesting ability induced by the axially coordinated N1. Furthermore, the two additives also can be used to fabricate efficient solar cells based on the wrapped porphyrin dye XW42, achieving high efficiency of 10.3%, indicative of their general applicability in fabricating high-performance DSSCs. These results indicate that the simultaneous employment of the traditional TBP additive and a pyridyl ligand with light-harvesting ability in the electrolyte for the axial coordination to a porphyrin dye is a promising approach for developing efficient DSSCs.

Organic semiconducting materials from sulfur-hetero benzo[k]fluoranthene derivatives: synthesis, photophysical properties, and thin film transistor fabrication.

A new family of air-stable sulfur-hetero oligoarenes based on the benzo[k]fluoranthene unit has been facilely developed as the active materials for thin film organic field-effect transistors. The Diels-Alder reaction between cyclopentadienone 1 and 2,2'-(ethyne-1,2-diyl)bisthiophene followed by decarbonylation afforded fluoranthene derivative 2. After bromination and subsequent substitution through Suzuki coupling reaction, the FeCl3-oxidative cyclization produced sulfur-hetero benzo[k]fluoranthene derivatives 8-12. In dilute chloroform solution, the absorption and emission behaviors of 2 and 4-7 showed characteristic features of the fluoranthene units, while their emission lambda(max) red-shifted with an increase of the effective conjugation length. The steady state absorption and emission spectra of these newly synthesized compounds were thoroughly investigated and discussed. Thin film organic field-effect transistors (OFETs) using 8-11 as active materials were fabricated in a "top contact" configuration. Substituents at the skeleton play an important role in the film morphologies, which lead to different mobilities, while the charge mobilities of 8-11 from OFETs were improved after thermal annealing of the thin films. A carrier mobility as high as 0.083 cm(2) V(-1) s(-1) and current on/off ratio of 10(6) were achieved through vacuum-deposited film followed by the thermal annealing process from 11.

Cyano- and chloro-substituted coronene diimides as solution-processable electron-transporting semiconductors.

3,4,9,10-Tetracyano- and tetrachlorocoronene-1,6,7,12-tetracarboxy diimides with low LUMO levels at -3.9 to -4.2 eV are developed. These molecules manifest potent n-type semiconductive capability in solution-processed field-effect transistors, with electron mobilities of up to 0.16 cm(2) V(-1) s(-1) measured in air. The device performances of analogous molecules elucidate the importance of side chain structures in the semiconductive properties.

Carbon-bridged oligo(p-phenylenevinylene)s for photostable and broadly tunable, solution-processable thin film organic lasers.

Thin film organic lasers represent a new generation of inexpensive, mechanically flexible devices for spectroscopy, optical communications and sensing. For this purpose, it is desired to develop highly efficient, stable, wavelength-tunable and solution-processable organic laser materials. Here we report that carbon-bridged oligo(p-phenylenevinylene)s serve as optimal materials combining all these properties simultaneously at the level required for applications by demonstrating amplified spontaneous emission and distributed feedback laser devices. A series of six compounds, with the repeating unit from 1 to 6, doped into polystyrene films undergo amplified spontaneous emission from 385 to 585 nm with remarkably low threshold and high net gain coefficients, as well as high photostability. The fabricated lasers show narrow linewidth (<0.13 nm) single mode emission at very low thresholds (0.7 kW cm(-2)), long operational lifetimes (>10(5) pump pulses for oligomers with three to six repeating units) and wavelength tunability across the visible spectrum (408-591 nm).

Water-soluble triscyclometalated organoiridium complex: phosphorescent nanoparticle formation, nonlinear optics, and application for cell imaging.

Two water-soluble triscyclometalated organoiridium complexes, 1 and 2, with polar side chains that form nanoparticles emitting bright-red phosphorescence in water were synthesized. The optimal emitting properties are related to both the triscyclometalated structure and nanoparticle-forming ability in aqueous solution. Nonlinear optical properties are also observed with the nanoparticles. Because of their proper cellular uptake in addition to high emission brightness and effective two-photon absorbing ability, cell imaging can be achieved with nanoparticles of 2 bearing quaternary ammonium side chains at ultra-low effective concentrations using NIR incident light via the multiphoton excitation phosphorescence process.

Intramolecular Interactions of Highly π-Conjugated Perylenediimide Oligomers Probed by Single-Molecule Spectroscopy.

Highly π-conjugated perylenediimide (PDI) oligomers are promising low band gap organic materials for various applications in optoelectronics. In this work, individual fluorescence dynamics of ethynylene- and butadiynylene-bridged dimeric and trimeric PDIs (PEP, PBP, and PEPEP) were monitored and analyzed by single-molecule fluorescence spectroscopy to gain information on the degree of extension of π-conjugation through the acetylene bridge in PDI multichromophores. The simultaneous measurements of fluorescence intensity, lifetime, and spectrum indicate a sequential decrease in π-conjugation upon photobleaching of PDI monomer units. Furthermore, Huang-Rhys (HR) factors, S, are obtained to evaluate the degree of electronic coupling in view of π-conjugation and overall rigidity between the PDI units in PDI oligomers at the single-molecule level. In addition, butadiynylene-bridged dimeric PDI (PBP) reveals conformational heterogeneity due to the long butadiynylene linker. These results suggest a new way to control the photophysical properties of the PDI multichromophoric system by expansion of π-conjugation and modification with different linker groups.

Electron-transporting PAHs with dual perylenediimides: syntheses and semiconductive characterizations.

An effective method was developed to prepare triphenyleno[1,2,3,4-ghi]perylenediimide derivatives, via ICl-induced annulation, dehalogenation, followed by photocyclization. A perylenediimide (PDI) dimer featuring a terphenyl bisethynylene linker was thereby transformed into a benzo[k]tetraphene fused with two benzoperylenediimides. These PDI derivatives exhibited electron mobility up to 0.079 cm(2) V(-1) s(-1) in solution-processed thin film transistors.

Pressure accelerated 1,3-dipolar cycloaddition of azide and alkyne groups in crystals.

The cycloaddition of azides and alkynes in the solid state was accelerated by high pressure. In situ Raman scattering and synchrotron X-ray diffraction were employed to study reaction kinetics at different pressures which revealed that the pressure acceleration originates from the elevated substrate energy and decreased activation energy.