A synergetic interaction between two or more photochromic chromophores has a potential to achieve advanced photochemical properties beyond conventional photochromic molecules and to realize photochemical control of complex systems using only a single molecule. Herein, we report a hybrid photochromic molecule consisting of hexaarylbiimidazole (HABI) and terarylene that exhibits multi-state photochromism. The biphotochrome hybrid shows four-state photochromic reaction involving sequentially proceeding photoreactions. The UV or visible light irradiation to the biphotochrome leads to the C-N bond breaking reaction of the HABI in preference to the ring-closing reaction of the 6π-electron system in the terarylene unit, leading two terarylene radical molecules. The photogenerated terarylene radical further exhibits the 6π-electrocyclization reaction by UV irradiation. The delocalized π-radical on the closed-ring form of the terarylene is efficient to enhance the photosensitivity to the NIR-I and -II region. Furthermore, a recombination reaction of radicals between the open- and closed-ring isomers of terarylene affords an unprecedented photochromic dimer as a structural isomer of the initial molecule. This is a consequence of the sequential hybrid photochromic system involving the HABI and terarylene units.
BACKGROUND: Appendiceal bleeding is very rare, accounting for about 0.4% of all lower gastrointestinal bleeding. We present a case of laparoscopic appendectomy in a patient with a diagnosis of appendiceal bleeding. CASE PRESENTATION: A 71-year-old man came to our hospital with a complaint of bloody stools. He had progressive anemia and persistent fresh bloody stools, so he underwent lower gastrointestinal endoscopy. Active bleeding was confirmed from the orifice of the appendix, but the bleeding could not be stopped even with clips, so an emergency laparoscopic appendectomy was performed. His postoperative course was good, and he was discharged on the third postoperative day. Although the pathology results did not allow identification of the source of the bleeding, an appendiceal diverticulum was observed, and appendiceal diverticular bleeding was suspected. CONCLUSION: Appendiceal bleeding is often difficult to stop endoscopically, so appendectomy should be performed as soon as possible.
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.
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.
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.
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.
We synthesized a series of MAu12 (dppe)5 Cl2 (MAu12 ; M=Au, Pd, Pt, Rh, or Ir; dppe=1,2-bis(diphenylphosphino)ethane), which have icosahedral M@Au12 superatomic cores, and systematically investigated their electronic structures, photoluminescence (PL) and photocatalytic properties. The energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) was expanded when doping an M element positioned at the lower left of the periodic table. The PL quantum yield was enhanced with an increase in the HOMO-LUMO gap and reached 0.46-0.67 for MAu12 (M=Pt, Rh, or Ir) under deaerated conditions. The bright PLs from MAu12 (M=Pt, Rh, or Ir) were assigned to phosphorescence based on quenching by O2 . MAu12 (M=Pt, Rh, or Ir) acted as a more efficient and stable photocatalyst than Au13 for intramolecular [2+2] cycloaddition of bisenone via the oxidative quenching cycle. This study provides rational guides for designing photoluminescent and photocatalytic gold superatoms by the doping of heterometal elements.
A 60-year-old woman with an abnormality discovered during a chest X-ray was referred to the authors' hospital for diagnosis and treatment. Upon enhanced computed tomography (CT), endoscopic ultrasonography, and magnetic resonance imaging, a tumor on the left side of the lower thoracic esophagus was detected. We diagnosed mediastinum cyst. One year after the first visit, a CT examination confirmed an increase in lesion size. Therefore, surgery was performed using a left thoracoscopic approach in the prone position. Before surgery, 3D models were used for simulation. Excision was performed without leakage of the contents. The histopathological diagnosis was a bronchogenic cyst. The left thoracoscopic surgery in the prone position is an uncommon approach but is useful for resecting tumors in the left side of the lower mediastinum. The authors were well-prepared and able to perform safe and reliable surgery.
Bronchogenic Cyst , Bronchogenic Cyst/diagnostic imaging , Bronchogenic Cyst/surgery , Esophagus/surgery , Female , Humans , Mediastinum/surgery , Middle Aged , Prone Position , Thoracoscopy
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.
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.
A series of doped gold superatoms M@Au12 (M = Ru, Rh, Ir) was synthesized by capping with the bidentate ligand (Ph2)PCH2P(Ph2). A single-crystal X-ray diffraction analysis showed that all the M@Au12 superatoms had icosahedral motifs with a significantly higher symmetry than that of the pure Au13 counterpart due to different coordination geometries. The Ru@Au12 superatom exhibited a room-temperature phosphorescence with the highest quantum yield of 0.37 in deaerated dichloromethane. Density functional theory calculations suggested that the efficient phosphorescence is ascribed to a rapid intersystem crossing due to the similarity between the singlet and triplet excited states in terms of structure and energy.
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.
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.
Fluorescence Resonance Energy Transfer , Fluorescent Dyes/chemistry , Nanoparticles/chemistry , Infrared Rays , Microscopy, Fluorescence , Molecular Structure , Photochemical Processes
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.
A molecular motor that has been previously shown to rotate when fueled by electrons through a scanning tunneling microscope tip has been functionalized with a terarylene photochrome fragment on its rotating subunit. Photoisomerization has been performed under UV irradiation. Variable-temperature 1H NMR and UV-vis studies demonstrate the rotational motion and its braking action after photoisomerization. The braking action can be reversed by thermal heating. Once the rigid and planar closed form is obtained, the rotation is effectively slowed at lower temperature, making this new rotor a potential motor with an independent response to electrons and light.
The oxidation of alcohols to aldehydes is a powerful reaction pathway for obtaining valuable fine chemicals used in pharmaceuticals and biologically active compounds. Although many oxidants can oxidize alcohols, only a few hydrogen peroxide oxidations can be employed to continuously synthesize aldehydes in high yields using a liquid-liquid two-phase flow reactor, despite the possibility of the application toward a safe and rapid multi-step synthesis. We herein report the continuous flow synthesis of (E)-cinnamaldehyde from (E)-cinnamyl alcohol in 95%-98% yields with 99% selectivity for over 5 days by the selective oxidation of hydrogen peroxide using a catalyst column in which Pt is dispersed in SiO2. The active species for the developed selective oxidation is found to be zero-valent Pt(0) from the X-ray photoelectron spectroscopy measurements of the Pt surface before and after the oxidation. Using Pt black diluted with SiO2 as a catalyst to retain the Pt(0) species with the optimal substrate and H2O2 introduction rate not only enhances the catalytic activity but also maintains the activity during the flow reaction. Optimizing the contact time of the substrate with Pt and H2O2 using a flow reactor is important to proceed with the selective oxidation to prevent the catalytic H2O2 decomposition.
Helicenes are promising candidates for chiral optoelectronic materials because of their helically twisted π-conjugated system. However, the emission intensity of unsubstituted helicenes is very weak (Φf < 0.05) due to a small oscillator strength for the S1 â S0 transition. In this work, we investigated the substitution position of the [7]helicene framework so that the S1 â S0 transition has a large transition magnetic dipole moment (TMDM) and is partially symmetry-allowed. A [7]helicene derivative thus designed showed a large fluorescence emission rate (kf = 0.02 ns-1) and a large TMDM for the S1 â S0 transition (|m| = 2.37 × 10-20 erg·Gauss-1), which are more than 10 times greater than those of unsubstituted [7]helicene (kf = 0.001 ns-1, |m| = 0.045 × 10-20 erg·Gauss-1). As a result, we achieved the [7]helicene derivative whose dissymmetry factor of CPL and fluorescence quantum yield were both high (|gCPL| = 1.3 × 10-2, Φf = 0.17) in the solution phase.
BACKGROUND: Postoperative anastomotic stenosis is a common complication in colorectal cancer patients (3-30%). Complete anastomotic stenosis is rare; however, when it occurs, almost all cases require surgical treatment. We herein report a case in which endoscopic dilation was effective for treating complete anastomotic stenosis after high anterior resection in a rectal cancer patient. CASE PRESENTATION: The patient was a 67-year-old man who underwent laparoscopic high anterior resection for rectal cancer (RS, T4a, N0, M0, Stage IIB (TNM Classification of Malignant Tumors)) in May 2018. The postoperative course was good and the patient was discharged on the 12th postoperative day. Subsequently adjuvant chemotherapy was initiated with oral uracil and tegafur plus leucovorin (UFT/LV); however, he complained of frequent defecation and melena after completion of the first course of chemotherapy. Thus, colonoscopy was performed, which revealed anastomotic stenosis. Endoscopic dilation was initially attempted, but failed. Thus, low anterior resection was performed with diverting colostomy. Four additional courses of chemotherapy were administered for 1 month after surgery. At 6 months after the second surgery, colonoscopy was performed, and complete anastomotic stenosis was pointed out again. The patient was successfully treated by endoscopic dilation using the rendezvous method. After this treatment, the lumen of the anastomotic site was observed to have narrowed again and endoscopic dilatation to treat anastomotic stenosis was repeated. In addition, he received local injection of steroids in anastomotic stenosis site. The lumen of anastomotic stenosis remained after the local injection of steroids and closure of colostomy was performed 9 months after the second operation. CONCLUSIONS: Endoscopic dilation using the rendezvous method was effective for treating anastomotic stenosis after colorectal surgery.
Rectal Neoplasms , Aged , Anastomosis, Surgical/adverse effects , Constriction, Pathologic/etiology , Dilatation , Humans , Male , Prognosis , Rectal Neoplasms/surgery , Retrospective Studies
CdTe nanoparticles capped with a cationic thiolate ligand were stably dispersed in ionic liquids, 1-alkyl-1-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)amides with an alkyl group of n-propyl, butyl and octyl-chain, and in an ionic plastic crystal, 1-ethyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)amide. Dispersion behavior of CdTe nanoparticles in these ionic media was evaluated, in which the solvation of nanoparticles by the ionic components was particularly interested. The ionic media showed alkyl-chain length-dependent solvation behavior, which was suggested by the thermal analysis of nanocomposites. The longer alkyl-chains led to the greater decrease in the thermal melting enthalpy of ionic media with the introduction of nanoparticles. The ionic liquid with an octyl-chain, which is considered to form a thicker solvation layer, afforded better emission durability of CdTe nanoparticles compared to the ionic liquid with a shorter alkyl chain.
