Cascade Fluorescence Modulation in Photochromic Microcapsules.

Certain derivatives of terarylene are able to undergo a highly efficient oxidative cycloreversion cascade effect, a ring opening reaction with quantum yields above unity, resulting in a colored-to-colorless transition in solution. In the presence of chloroform, high-energy UV and X-rays can trigger this phenomenon, potentially acting as a visual detection system for ionizing radiation. However, chloroform is sensitive to different irradiation wavelengths without distinction, making it difficult to adapt to a reusable device. Chlorobenzene was chosen as an alternative halogenated solvent, as it offers wavelength selectivity between photocyclization and cascade effect cycloreversion. Nile Red was also incorporated into the system with the aim of improving the sensitivity of the visual detection via fluorescence photoswitching. Finally, microencapsulation of both terarylene and Nile Red was targeted to obtain both the cascade effect and photoswitching in a single system. In microcapsules made from a Pickering emulsion, this terarylene-Nile Red system showed high fatigue resistance to repeated photocyclization and cycloreversion irradiation, giving access to repeated ON/OFF fluorescence photoswitching. The cascade effect was also successfully demonstrated along with fluorescence recovery, showing the versatility of the two phenomena in different media.

Synthesis and Spectroscopic Properties of Diarylethene-Subporphyrinoid Hybrids.

Two novel diarylethene-fused subporphyrinoids were prepared and characterized. A mono diarylethene derivative was obtained via a statistical condensation reaction with 2 eq. of 1,2-dicyanobenzene and 1 eq. of thiophene-disubstituted butenedinitrile. The symmetric triply diarylethene-fused subporphyrazine was synthesized via a cyclotrimerization reaction of the thiophene-disubstituted butenedinitrile derivative. These compounds were characterized by NMR spectroscopy and high-resolution mass spectrometry. The spectroscopic properties have been measured in hexane and in chloroform. The mono diarylethene-fused-type compound showed photochromism at 580 nm and >700 nm wavelength, accompanied by degradation. According to DFT calculations, photoreactivity likely depends on the contribution of aromatic feature of pyrrole ring bonded to two thiophene rings.

Semiconducting Carbon Nanotube Extraction Enabled by Alkylated Cellulose Wrapping.

With the growing demand for postsilicon electronics, the purification of single-walled carbon nanotubes (SWCNTs) in terms of their chirality, which defines their atomic and electronic structure, is becoming increasingly important. Herein, we demonstrate the selective extraction of high-quality semiconducting SWCNTs using alkyl cellulose as a dispersant in organic solvents. We investigated the separation factors of dispersant structures, such as the degree of substitution (DS) and molecular weight, and clarified the appropriate dispersant structures, such as moderately substituted hexyl cellulose, for selective semiconducting SWCNT extraction. Due to the improved purity and quality of the semiconducting SWCNTs obtained by this method, their films exhibit excellent thermoelectric power factors, outperforming not only unsorted SWCNTs but also conducting polymer-sorted SWCNTs. This sorting technology paves the way for supplying high-quality semiconducting SWCNTs in a viable manner.

Synthetic Utilization of 2H-Heptafluoropropane: Ionic 1,4-Addition to Electron-Deficient Carbon-Carbon Unsaturated Bonds.

We have found a novel method for introducing heptafluoro-2-propyl CF(CF3)2 groups into carbon-carbon unsaturated bonds via a nucleophilic reaction using 2H-heptafluoropropane as the source of CF(CF3)2 groups. The reaction involves the nucleophilic addition of a heptafluoro-2-propyl anion, generated by treating 2H-heptafluoropropane with a fluoride ion, to various electron-deficient unsaturated compounds. This allows the easy synthesis of various aliphatic compounds containing heptafluoro-2-propyl groups.

C3-Symmetric Luminescent Diketone with Amido-Linkage as a Polymorphic Fluorescence Emitter.

The study introduces a novel C3-symmetric ß-diketone compound, BTA-D3, and its monomeric counterpart, D, with a focus on their synthetic procedure, photophysical properties and aggregation behavior. Both compounds exhibit characteristic absorption and weak fluorescence in solution, with BTA-D3 displaying higher absorption coefficients due to its larger number of diketone units. Density Functional Theory (DFT) calculations suggest increased co-planarity of diketone groups in BTA-D3. A significant finding is the Aggregation-Induced Emission (AIE) property of BTA-D3, as its fluorescence intensity increases dramatically when exposed to specific solvent ratios. The AIE behavior is attributed to intermolecular excitonic interaction between BTA-D3 molecules in self-organized aggregates. We also studied fluorescence anisotropy of BTA-D3 and D. Despite its larger size, BTA-D3 showed reduced anisotropy values because of efficient intramolecular energy migration among three diketone units. Furthermore, BTA-D3 demonstrates unique polymorphism, yielding different emission colors and structures depending on the solvent used. A unique approach is presented for promoting the growth of self-organized aggregate structures via solvent evaporation, leading to distinct fluorescence properties. This research contributes to the understanding of C3-symmetric structural molecules and provides insights into strategies for controlling molecular alignment to achieve diverse fluorescence coloration in molecular materials.

Synthesis and Photochromic Properties of Diaryl [5]Helicene Derivatives.

Photoinduced tuning of aromaticity and correlative molecular properties has attracted enormous interest in recent years both for modulating photochromism properties and designing novel photochromic materials. Here, we report the synthesis and photochemical characterization of diaryl[5]helicene-based diarylethene molecular switches. 3,4-Bis(2,4-dimethyl-5-phenylthiophen-3-yl)dibenzo[c,g]phenanthrene derivative 1 a showed no photochromic reaction, whereas 3,4-bis(2-methyl-5-phenylthiophen-3-yl)dibenzo[c,g]phenanthrene derivative 2 a and 3,4-bis(5-methyl-2-phenylthiazol-4-yl)dibenzo[c,g]phenanthrene derivative 3 a exhibited reversible photochromism in different aprotic solvents with specific light irradiation. Meanwhile, the diarylethene compounds 2 a and 3 a underwent turn-off mode fluorescence photoswitching together with photoisomerization upon light irradiation. Remarkably, the photoinduced changes in the aromaticity of [5]helicene as a central ethene bridge along with the relative smaller activation energy and higher frequency factor facilitated the thermal bleaching rates of diarylethene switches 2 and 3 in solution. This research provides new insight for designing aromatic diarylethene photoswitches for reversible fluorescence switching, photoinduced changes in aromaticity and further fast thermal back reactions.

Excited State Engineering in Ag29 Nanocluster through Peripheral Modification with Silver(I) Complexes for Bright Near-Infrared Photoluminescence.

The optical property of an ionic metal nanocluster (NC) is affected by the ionic interaction with counter ions. Here, we report that the modification of trianionic [Ag29(BDT)12(TPP)4]3- NC (BDT: 1.3-benzenedithiol; TPP: triphenylphosphine) with silver(I) complexes led to the intense photoluminescence (PL) in the near-infrared (NIR) region. The binding of silver(I) complexes to the peripheral region of Ag29 NC is confirmed by the single-crystal X-ray diffraction (SCXRD) measurement, which is further supported by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. The change of excited-state dynamics by the binding of silver(I) complexes is discussed based on the results of a transient absorption study as well as temperature-dependent PL spectra and PL lifetime measurements. The modification of Ag29 NCs with cationic silver(I) complexes is considered to give rise to a triplet excited state responsible for the intense NIR PL. These findings also afford important insights into the origin of the PL mechanism as well as the possible light-driven motion in Ag29-based NCs.

Conglomerate, Racemate, and Achiral Crystals of Polymetallic Europium(III) Compounds of Bis- or Tris-ß-diketonate Ligands and Circularly Polarized Luminescence Study.

This work reports (a) conglomerate and racemic crystal structures of [(Δ,Δ,Δ,Δ,Δ,Δ)- or/and (Λ,Λ,Λ,Λ,Λ,Λ)-EuIII 6(TTP)8(OH2)6Na4] n coordination polymers, (b) racemic crystal structures of (Δ,Δ,Δ,Δ)-/(Λ,Λ,Λ,Λ)-EuIII 4(TTP)4(bipy)4(MEK)2(OH2)2 tetrahedral clusters, and (c) the achiral crystal structure of the [EuIII 2(BTP)4(OH2)2Na2] n coordination polymer (where BTP = dianionic bis-ß-diketonate, TTP = trianionic tris-ß-diketonate, and bipy = 2,2'-bipyridine). The screw coordination arrangement of the TTP ligand has led to the formation of homoconfigurational racemic EuIII products. The conglomerate crystallization of [EuIII 6(TTP)8(OH2)6Na4] n appears to be caused by the presence of the sodium, Na+ counterions, and interactions between oxygen atoms and the trifluoromethyl unit of the TTP ligand and Na+ ions. All the EuIII compounds exhibit characteristic red luminescence (5D0 → 7FJ, J = 0-4) in solution or in the solid crystalline state. Circularly polarized luminescence (CPL) was observed in the chiral EuIII 6(TTP)8(OH2)6Na4] n species, displaying a |g lum| value in the range of 0.15 to 0.68 at the 5D0 → 7F1 emission band. Subtle changes of the [EuIII 6(TTP)8(OH2)6Na4] n structure which may be due to selection of twinned crystals or crystals that do not correspond to a perfect spontaneous resolution, are considered to be responsible for the variation in the observed CPL values.

Cationic Rhodium(I)-Catalyzed Asymmetric Cyclohydroformylation of 1,6-Enynes with Formaldehyde.

We report a rhodium(I)-catalyzed asymmetric cyclohydroformylation reaction of 1,6-enynes with formaldehyde. The reaction of 1,6-enynes with formaldehyde in the presence of a cationic Rh(I) catalyst, such as [Rh(cod)2 ]+ OTf- , and a chiral biaryl diphosphine led to asymmetric cyclohydroformylation to produce aldehydes with higher-order structures highly enantioselectively. This transformation procedure is applicable to a variety of enynes, with wide compatibility in various atoms liking between the alkyne and alkene parts, substituents at the alkyne terminus, and substituents at the alkene part, being converted to newly formed aldehydes in 14% to 90% yields with 50% to 98% ee. The products were further transformed with various nucleophiles to alcohols, an amine, and a diene without loss of chirality at their γ-position.

From Visible to Near-Infrared Light-Triggered Photochromism: Negative Photochromism.

Photochromic compounds, whose key molecular properties can be effectively modulated by light irradiation, have attracted significant attention for their potential applications in various research fields. The restriction of photoisomerization coloration induced by ultraviolet light limits their applications in the biomedical field and some other fields. Negative photochromism, wherein a relatively stable colored isomer transforms to a colorless metastable isomer under low-energy light irradiation, offers advantages in applications within materials science and life science. This review provides a summary of negatively photochromic compounds based on different molecular skeletons. Their corresponding design strategies and photochromic properties are presented to provide practical guidelines for future investigations. Negatively photochromic compounds can effectively expand the range of photochromic switches for future applications, offering unique properties such as responsiveness to visible to near-infrared light.

A Case of Esophagojejunal Variceal Rupture after Total Gastrectomy and Esophagojejunostomy Successfully Treated with Percutaneous Transhepatic Obliteration under Dual-balloon Occlusion of Feeding and Draining Veins.

We present the case of a man in his 60s with bleeding esophagojejunal varices occurring after gastrectomy for gastric carcinoma. Percutaneous transhepatic portography depicted the esophagojejunal varices originated from the jejunal vein and drained into the azygos vein. A 5-French occlusion balloon catheter was wedged into the jejunal vein and a 3-French occlusion balloon catheter into one drainage channel of the esophagojejunal varices via the azygos vein. Selective antegrade jejunal venography under dual-balloon occlusion revealed entire esophagojejunal varices with good stagnated and well-opacified contrast medium. Subsequently, 12 mL of 5% ethanolamine oleate-contrast medium mixture was slowly injected into the esophagojejunal varices. He was discharged without complications one week after the procedure, and abdominal computed tomography demonstrated the disappearance of the esophagojejunal varices six months after the procedure.

Tetrathienyl Corannulene Compounds with Highly Sensitive Photochromism.

We have designed and synthesized photochromic tetrathienyl corannulene compounds, 1,2,7,8-tetrakis(2-methyl-5-phenylthiophen-3-yl)corannulene (1) and 1,2,7,8-tetrakis(2,4-dimethyl-5-phenylthiophen-3-yl)corannulene (2), by fusing two units of photochromic terarylene with a curved aromatic corannulene with a promising antenna effect. Compound 1 exhibited highly sensitive photoreactivity, with a large molar absorption coefficient of 8.2×104  M-1 cm-1 and practically photon-quantitative photocyclization. On the other hand, a terarylene derivative with a planar aromatic phenanthrene, 9,10-bis(2,4-dimethyl-5-phenylthiophen-3-yl)phenanthrene (4) showed no photoreactivity. The reason for such a difference was attributed to the predominance of the photoreactive atropisomers amplified by energy migration, and the shortened distance between reactive carbons induced by the curved structure.

Self-Regulated Pathway-Dependent Chirality Control of Silver Nanoclusters.

Imparting chirality affords additive values, functions and responsiveness in molecular systems including nanoscale materials. Here, we report pathway-dependent chirality control in silver nanoclusters (NCs). The use of enantiomeric ligand, α-dihydrolipoic acid (DHLA), for the synthesis of Ag NCs leads to the preferential formation of one-handed chiral Ag29 (DHLA)12 NCs with intrinsic chirality in the exterior shell composed of a silver-dithiolate framework. Small Lewis base molecules such as pyridine bind to silver atoms in the shell of NC as a guest. The guest binding reverses the relative stability between the right- and left-handed NCs upon a steric interaction with the chiral ligand DHLA in the exterior shell in a kinetic manner, leading to unprecedented chirality inversion in the synthesis of NCs. This mechanism is further extended to the self-regulation or self-replication of chirality through interNC interactions dependent on the concentration in the synthesis of NCs.

Circularly Polarized Luminescence and Circular Dichroism of Bichromophoric Difluoroboron-ß-diketonates: Inversion and Enhanced Chirality Based on Spatial Arrangements and Self-Assembly.

We synthesized two bichromophoric difluoroboron-ß-diketonates (DFB) connected in para and meta positions by using cyclohexane diamine as a chiral bridge (para and meta (R/S)-CyDFB). TD-DFT calculations revealed that the variation in connectivity of the DFB units leads to different spatial arrangements and a chirality inversion of the bichromophoric DFB. Higher gabs values were obtained in (R/S)-CyDFB connected in para as compared to meta position. Aggregation of para (R/S)-CyDFB in mixture of solvents increase the glum values as compared to its monomeric form. Ultrasonication and heating induced the formation of highly ordered nano-helical wires of para (R/S)-CyDFB that increased the glum values to 0.015. On the other hand, meta (R/S)-CyDFB failed to form highly ordered self-assembled wires due to hindered H-binding sites. These observations indicate that the chiroptical properties of DFB bi-chromophore system can be modulated with self-assembly and spatial arrangement of the chromophores.

Chiral Dinuclear EuIII , TbIII , and YIII Complexes Supported by P-Stereogenic Linear Tetraphosphine Tetraoxide.

A P-stereogenic linear tetraphosphine tetraoxide, (R,R)- or (S,S)-dpmppm(=O)4 , was synthesized to prepare C2 dinuclear M(hfa)3 complexes (M=Eu, Tb, Y) as the first example of lanthanide(III) complexes with P-chiral multidentate phosphine oxides. The mononuclear M(hfa)3 complexes (M=Eu, Y) with a P-chiral diphosphine dioxide, tpdpb(=O)2 , were also prepared, and comparison of their photophysical properties for the EuIII complexes revealed that significant chiral induction from the P-chiral centers arises on the achiral M(hfa)3 units through intramolecular π-π stacking constraint in the dinuclear system.

Energy Storage upon Photochromic 6-π Photocyclization and Efficient On-Demand Heat Release with Oxidation Stimuli.

Photochromic molecules display reversible isomerization reactions between two isomers accompanied by an exchange between heat and chemical potential. A considerable part of the absorbed light energy is stored in and released from the present E-type photochromic molecules, which undergo cyclization reactions under UV light excitation and backward reactions after application of oxidative stimuli. The photochromic nature, thermal stability, and cascade ring-opening reaction of the closed form isomers of eight photochromic terarylenes are studied, and energy storage efficiencies at a single wavelength, η, as high as 23% are experimentally demonstrated. Their efficient photochemical quantum yield for the cyclization reaction markedly contributes to the high energy storage efficiency as well as showing the capability of efficient cascade cycloreversion reactions. Spontaneous cycloreversion reactions are well-suppressed because the forbidden nature of the cycloreversion reaction gives rise to sufficient heat storage duration.

Generation of Tetrafluoroethylene-Propylene Elastomer-Based Microfluidic Devices for Drug Toxicity and Metabolism Studies.

Polydimethylsiloxane (PDMS) is widely used to fabricate microfluidic organs-on-chips. Using these devices (PDMS-based devices), the mechanical microenvironment of living tissues, such as pulmonary respiration and intestinal peristalsis, can be reproduced in vitro. However, the use of PDMS-based devices in drug discovery research is limited because of their extensive absorption of drugs. In this study, we investigated the feasibility of the tetrafluoroethylene-propylene (FEPM) elastomer to fabricate a hepatocyte-on-a-chip (FEPM-based hepatocyte chip) with lower drug absorption. The FEPM-based hepatocyte chip expressed drug-metabolizing enzymes, drug-conjugating enzymes, and drug transporters. Also, it could produce human albumin. Although the metabolites of midazolam and bufuralol were hardly detected in the PDMS-based hepatocyte chip, they were detected abundantly in the FEPM-based hepatocyte chip. Finally, coumarin-induced hepatocyte cytotoxicity was less severe in the PDMS-based hepatocyte chip than in the FEPM-based hepatocyte chip, reflecting the different drug absorptions of the two chips. In conclusion, the FEPM-based hepatocyte chip could be a useful tool in drug discovery research, including drug metabolism and toxicity studies.

The emergence of intense near-infrared photoluminescence by photoactivation of silver nanoclusters.

Photoirradiation of a pyridine solution of Ag29 nanoclusters (NCs) with red photoluminescence (PL) at 680 nm activated intense PL in the near infrared (NIR) region, giving a PL quantum yield (PLQY) of 33% at 770 nm. The use of Au-doped silver NCs further boosted the PLQY to more than 45% at 800 nm. Photoirradiation is considered to induce a change in the charge localization in the NCs, leading to the formation of NIR emitting sites.

Efficient NIR-I fluorescence photoswitching based on giant fluorescence quenching in photochromic nanoparticles.

A photoswitchable near-infrared (NIR) fluorescent nanoparticle (NP) was designed and prepared. The NP showed a characteristic AIE property and high-contrast NIR fluorescence photoswitching with full reversibility. Such efficient NIR fluorescence photoswitching originated from the amplified fluorescence quenching mechanism based on intermolecular energy transfer in a densely packed NP state.

Supramolecular Copolymerization of Bichromophoric Chiral and Achiral Perylenediimide Dyes.

Propagation and amplification of chirality are considered to play an important role in the chemical evolution of biological homochirality. Stereochemical communications have been demonstrated to have a significant effect on the formation of chiral hierarchical structures in helical polymers, surface assemblies and supramolecular polymers. The formation of supramolecular copolymers based on chiral and achiral bichromophoric perylenediimide (PDI) dyes having a binaphtyl- and biphenyl-core-bridging unit, respectively, was investigated in terms of chiral amplification and propagation. The biphenyl-bridged PDI dye was expected to perform as a prochiral component to adopt both right- and left-handed twisting structures with the free rotation over the phenyl-phenyl linkage upon partnered with the chiral binaphtly PDI dye in the coassemblies. The coassemblies between the chiral and achiral PDI dyes with dissimilar core units demonstrated the composition dependent control in the length of supramolecular nanofibers as well as amplification of optical activity.