Enantioseparation via Chiral Supramolecular Gels Comprising Ambidextrous Gelators Based on ß-Peptide-type Primary Amines.

While ß-peptides have been paid attention due to their diverse secondary structures, their application to the design of low-molecular-weight gelators (LMWGs) is less explored. In this work, chiral cyclic ß-amino acid-based ß-peptides were developed as ambidextrous LMWGs, wherein multiple hydrogen bonds between the amide moieties led to high gelation ability. Their molecular assembly was elucidated using spectroscopies, microscopy, and X-ray analysis. Further, the supramolecular gel was used as a platform for the enantioselective extraction of (S)-naproxen from its racemate under optimized conditions. These findings have expanded the utility of ß-peptides and shown the potential of supramolecular gels as a distinct dynamic medium for enantiomer separation.

Enantiomer separation of 2-halomandelic acids via diastereomeric salt formation with chiral N-substituted 2-amino-2-phenylethanols.

Chiral N-substituted secondary 1,2-aminoalcohols have been developed for the enantioseparation of ortho-halomandelic acids (o-X-MAs) via diastereomeric salt formation. Two structural isomers, N-methyl-2-amino-1,2-diphenylethanol and N-benzyl-2-amino-2-phenylethanol, showed high separation abilities for o-X-MAs (X = Cl, Br, I). The chiral recognition mechanism was elucidated by crystallographic analysis of the less-soluble salts. The substituents on the nitrogen atom of the resolving agents and the inclusion of the crystallization solvent stabilized the salt and enhanced their separation ability.

Thermoreversible helical fibers from photoreactive triphenylene-derived liquid crystals in liquid paraffin.

Liquid crystalline triphenylene derivatives, TPC1p-n (n = 6, 12, 14, 16) were prepared using p-alkoxycinnamate as the [2+2] photo-cyclization site. TPC1p-n (n = 12, 14, 16) showed Colr phase and gave crescent-shaped or helical fibers after UV-irradiated in liquid paraffin solutions at 90 and 110 °C in the Colr temperature range. The apparent photoreaction products were shown to be thermally reversible, i.e. they dissolved in liquid paraffin at high temperatures and reappeared on cooling, indicating that they were aggregates of oligomerized TPC1p-n. The reaction mechanism was discussed in terms of the structure of the liquid crystalline phase.

Chemical Storage of Ammonia through Dynamic Structural Transformation of a Hybrid Perovskite Compound.

Toward renewable energy for global leveling, compounds that can store ammonia (NH3), a carbon-free energy carrier of hydrogen, will be of great value. Here, we report an organic-inorganic halide perovskite compound that can chemically store NH3 through dynamic structural transformation. Upon NH3 uptake, a chemical structure change occurs from a one-dimensional columnar structure to a two-dimensional layered structure by addition reaction. NH3 uptake is estimated to be 10.2 mmol g-1 at 1 bar and 25 °C. In addition, NH3 extraction can be performed by a condensation reaction at 50 °C under vacuum. X-ray diffraction analysis reveals that reversible NH3 uptake/extraction originates from a cation/anion exchange reaction. This structural transformation shows the potential to integrate efficient uptake and extraction in a hybrid perovskite compound through chemical reaction. These findings will pave the way for further exploration of dynamic, reversible, and functionally useful compounds for chemical storage of NH3.

Development of Low-Molecular-Weight Organogelators from Cyclic ß-Amino Acid: Effect of Stereochemistry and their Application on Visual Chiral Recognition of Amines.

This study reports the formation of low-molecular-weight gelators based on carboxylic acids derived from chiral cyclicß-amino acids. The effect of their stereochemistry on the gelation of organic solvents was investigated, and their assemblies with the intermolecular interactions in the xerogels were proposed via infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and crystallographic details of the related model compounds. The effect of the alkyl chain length on the gelators was studied, and they were applied to the chiral recognition of amines. Only one diastereomeric salt with amines afforded gels, whereas the others resulted in precipitates. Chiral recognition was also achieved in the gel state, and the appearance of the as-prepared gel changed upon the addition of each amine enantiomer, thus enabling the visual detection of their chirality.

Supramolecular Architecture of an Amphiphilic Amino Alcohol as a Versatile Chiral Environment for Stereocontrolled Photoreaction of Various Anthracenes.

The photocyclodimerization of 2-anthracenecarboxylic acid has been extensively studied as a model reaction of asymmetric photochemistry. So far, numerous chiral environments have been employed to control this photoreaction, while the scope of photoreactants has been limited only to 2-anthracenecarboxylic acid and its simple esters and amides. Here, we developed a systematic series of photoreactants (2 a-d) by introducing various substituents to 2-anthracenecarboxylic acid, which showed different reactivities and selectivities depending on the substituents. By using the photoreactants 2 a-d, we evaluated the performance of a chiral environment composed of an amphiphilic amino alcohol (1), where the photocyclodimerization of 2 a-d generally proceeded in excellent regio- and enantioselectivities (71-98 % regio ratio, 76-86 % ee). Furthermore, by reacting 2 a and 2 b together in the chiral environment of 1, we succeeded in the first stereocontrolled cross-photocyclodimerization between two prochiral anthracenes (58 % chemo ratio, 83 % regio ratio, 90 % ee).

Efficient preparation of stereopure amphiphilic 1,2-amino alcohols by using preparative enantioselective HPLC.

Chiral amphiphiles are useful for controlling the structures and properties of supramolecular assemblies, but their stereocontrolled synthesis is generally difficult, because their long alkyl chains tend to bring unfavorable effects on the solubility, reactivity, and crystallinity of molecules. Typical examples are amphiphilic 1,2-amino alcohols (S)-1 and (1S,2S)-2 developed by our group, which were known to serve as chiral reaction media for controlling the stereochemistry of asymmetric photoreactions. We previously developed synthetic schemes for these 1,2-amino alcohols, but their synthetic efficiencies were unsatisfactory (13 steps with 2% overall yield for (S)-1; eight steps with 8% yield for (1S,2S)-2). As the main reason of such low efficiencies, the stereocontrolling methods we previously employed (diastereomer-salt crystallization for (S)-1; stereoselective reactions for (1S,2S)-2) were not ideal. Here, we report highly improved synthetic schemes for (S)-1 and (1S,2S)-2 based on the enantioselective high performance liquid chromatography (HPLC) separation of intermediates in preparative scales. Compared with the previous schemes, the new schemes are advantageous in fewer number of steps, higher overall yield, and lower risk of racemization (seven steps with 15% overall yield for (S)-1; seven steps with 26% overall yield for (1S,2S)-2).

Enantioseparation of 3-Hydroxycarboxylic Acids via Diastereomeric Salt Formation by 2-Amino-1,2-diphenylethanol (ADPE) and Cinchonidine.

Enantioseparation of 3-hydroxycarboxylic acids via diastereomeric salt formation was demonstrated using 2-amino-1,2-diphenylethanol (ADPE) and cinchonidine as the resolving agents. Racemic 3-hydroxy-4-phenylbutanoic acid (rac-1), 3-hydroxy-4-(4-chlorophenyl)butanoic acid (rac-2), and 3-hydroxy-5-phenylpentanoic acid (rac-3) were efficiently resolved using these resolving agents. Moreover, the successive crystallization of the less-soluble diastereomeric salt of 1 and cinchonidine using EtOH yielded pure (R)-1 · cinchonidine salt in a high yield. The crystal structures of less-soluble diastereomeric salts were elucidated and it was revealed that hydrogen bonding and CH/π interactions play an important role in reinforcing the structure of the less-soluble diastereomeric salts.

Noncovalent Functionalization of Single-Walled Carbon Nanotubes with a Photocleavable Polythiophene Derivative.

Single-walled carbon nanotubes (SWCNTs) have received extensive research attention owing to their extraordinary optical, electrical, and mechanical properties, which make them particularly attractive for application in optoelectronic devices. However, SWCNTs are insoluble in almost all solvents. Therefore, developing methods to solubilize SWCNTs is crucial for their use in solution-based processes. In this study, we developed a photocleavable polythiophene-derivative polymer dispersant for SWCNTs. The noncovalent surface functionalization of SWCNTs with a polymer allows their dispersal in tetrahydrofuran. The resultant solution-processed polymer/SWCNT composite film undergoes a hydrophobic-to-hydrophilic change in surface properties upon light irradiation (313 nm) because hydrophilic carboxyl groups are formed upon photocleavage of the hydrophobic solubilizing units in the polymer. Furthermore, the photocleaved composite film displays a 38-fold increase in electrical conductivity. This is due to the removal of the solubilizing unit, which is electrically insulating.

Direct enantioseparation of axially chiral 1,1'-biaryl-2,2'-diols using amidine-based resolving agents.

Amidine-based optically active resolving agents for enantiomer separation of axially chiral 1,1'-biaryl-2,2'-diols have been developed. A strongly basic amidine bearing no substituents on its nitrogen atoms enables the formation of their diastereomeric salts upon being mixed with weakly acidic phenol derivatives. Enantiopure 1,1'-biaryl-2,2'-diols can be obtained in high yields after only one crystallization of their salts with the chiral amidine derived from dehydroabietic acid. X-ray crystallography revealed that the amidine moiety forms a salt with the phenol group and additional intermolecular NH/π interactions contribute to the efficient chiral recognition process.

Renal arteriovenous fistula induced by extracorporeal shock wave lithotripsy treated by retroperitoneoscopic nephrectomy.

Renal arteriovenous fistula (AVF) is a rare but potentially severe and life-threatening entity. It can occur after various invasive renal interventions, including resection of a localized renal tumor, renal biopsy, percutaneous renal surgery, and even blunt injury of the kidney. The time of clinical presentation of a renal AVF is variable and may occur decades after the injury originally occurred. Here, we report a case of renal AVF induced by extracorporeal shock wave lithotripsy 11 years earlier in an asymptomatic 72-year-old woman. Given the patient's pre-existing hemodialysis dependence, retroperitoneoscopic nephrectomy was performed. On the basis of patient's clinical history, the location of the renal AVF, and the pathological diagnosis, we suggested that renal AVF was a late consequence of the injury to the intrarenal vessels induced by extracorporeal shock wave lithotripsy.

Photocatalytic CO2 Reduction by Trigonal-Bipyramidal Cobalt(II) Polypyridyl Complexes: The Nature of Cobalt(I) and Cobalt(0) Complexes upon Their Reactions with CO2, CO, or Proton.

The cobalt complexes CoIIL1(PF6)2 (1; L1 = 2,6-bis[2-(2,2'-bipyridin-6'-yl)ethyl]pyridine) and CoIIL2(PF6)2 (2; L2 = 2,6-bis[2-(4-methoxy-2,2'-bipyridin-6'-yl)ethyl]pyridine) were synthesized and used for photocatalytic CO2 reduction in acetonitrile. X-ray structures of complexes 1 and 2 reveal distorted trigonal-bipyramidal geometries with all nitrogen atoms of the ligand coordinated to the Co(II) center, in contrast to the common six-coordinate cobalt complexes with pentadentate polypyridine ligands, where a monodentate solvent completes the coordination sphere. Under electrochemical conditions, the catalytic current for CO2 reduction was observed near the Co(I/0) redox couple for both complexes 1 and 2 at E1/2 = -1.77 and -1.85 V versus Ag/AgNO3 (or -1.86 and -1.94 V vs Fc+/0), respectively. Under photochemical conditions with 2 as the catalyst, [Ru(bpy)3]2+ as a photosensitizer, tri- p-tolylamine (TTA) as a reversible quencher, and triethylamine (TEA) as a sacrificial electron donor, CO and H2 were produced under visible-light irradiation, despite the endergonic reduction of Co(I) to Co(0) by the photogenerated [Ru(bpy)3]+. However, bulk electrolysis in a wet CH3CN solution resulted in the generation of formate as the major product, indicating the facile production of Co(0) and [Co-H] n+ ( n = 1 and 0) under electrochemical conditions. The one-electron-reduced complex 2 reacts with CO to produce [Co0L2(CO)] with νCO = 1894 cm-1 together with [CoIIL2]2+ through a disproportionation reaction in acetonitrile, based on the spectroscopic and electrochemical data. Electrochemistry and time-resolved UV-vis spectroscopy indicate a slow CO binding rate with the [CoIL2]+ species, consistent with density functional theory calculations with CoL1 complexes, which predict a large structural change from trigonal-bipyramidal to distorted tetragonal geometry. The reduction of CO2 is much slower than the photochemical formation of [Ru(bpy)3]+ because of the large structural changes, spin flipping in the cobalt catalytic intermediates, and an uphill reaction for the reduction to Co(0) by the photoproduced [Ru(bpy)3]+.

Extraperitoneal Rupture of a Bladder Diverticulum and the Role of Multidetector Computed Tomography Cystography.

Nontraumatic rupture of the bladder is less widely recognized than traumatic rupture, with a challenging early diagnosis due to high variability in clinical presentations. We report a case of extraperitoneal rupture of a bladder diverticulum in a patient with diabetes mellitus who presented with paralytic ileus. Despite conservative management, the patient developed sepsis requiring surgical treatment. Urinary tract infection and bladder outlet obstruction were considered to be potential mechanisms of the rupture. Multidetector computed tomography cystography should be used as the first-line modality when evaluating for a suspected bladder rupture, even in patients with nontraumatic bladder rupture.

Management of Ureterolithiasis in a Patient with Crossed Unfused Renal Ectopia.

Crossed renal ectopia is a rare congenital anomaly in which both kidneys are situated on one side and fused together in 85%-90% of cases. The management of urinary calculi in patients with crossed renal ectopia continues to pose challenges to urologists because the aberrant anatomy may make access and clearance of the calculi more difficult to accomplish. Here, we report a case of inferior crossed renal ectopia, without fusion, and a ureteral stone in which the patient was treated successfully by extracorporeal shock wave lithotripsy.

Laparoscopic Management of a Complex Adrenal Cyst.

Adrenal cysts are rare, and their clinical management remains controversial. We report a case involving an adrenal cyst with a complicated appearance on radiological studies. Unenhanced computed tomography revealed a unilocular, noncalcified, hypoattenuating mass with a thin wall in the left adrenal gland. The lesion gradually increased in size from 10 to 50 mm at two-year follow-up. On contrast-enhanced magnetic resonance imaging, a mural nodule with contrast enhancement was observed. The entire adrenal gland was excised en bloc via a lateral transperitoneal laparoscopic approach without violating the principles of surgical oncology. The pathological diagnosis was an adrenal pseudocyst. Laparoscopic adrenalectomy is a safe option for the treatment of complex adrenal cysts, while maintaining the benefits of minimal invasiveness.

Successful endovascular treatment using a covered stent for artery-ureteral fistula after surgery for abdominal aortic aneurysm.

Artery-ureteral fistula (AUF) is a rare condition but there is an increase in the number of reported cases. It is frequently difficult to treat. A 63-year-old male who had undergone a Dacron Y-graft placement for an infrarenal aortic aneurysm 3 years earlier, presented with hematuria. Contrast-enhanced computed tomography revealed a fistula located between the right common iliac artery and the right ureter at graft anastomosis. Endovascular treatment using a covered stent was performed successfully.

Inferior vena cava thrombosis associated with a distended ileal neobladder.

Venous stasis is generally accepted to be a predisposing factor for venous thrombosis. However, benign causes of inferior vena cava (IVC) obstruction with associated thrombus formation have not been well described. We herein present a case of IVC compression caused by a distended ileal neobladder measuring 2,000 mL in capacity that led to IVC thrombosis. Following transurethral drainage for six weeks and anticoagulation therapy with warfarin for six months, the thrombus completely disappeared. The patient was considered to have a hypercoagulable state resulting from an acute urinary tract infection, a condition that may be associated with an increased risk of thrombosis.

Synthesis of cyclic carbonates from CO2 and epoxides catalyzed by low loadings of benzyl bromide/DMF at ambient pressure.

An efficient, metal-free catalytic system for the conversion of CO2 and epoxides to cyclic carbonates under mild conditions with good-to-excellent yields (57-99%) was developed. A possible reaction mechanism involving the electrophilic activation of epoxides by benzyl cations and nucleophilic activation of CO2 by DMF is proposed.

Conservative management of a delayed neovesicocutaneous fistula.

A neovesicocutaneous fistula is a rare complication after orthotopic bladder reconstruction, particularly in the late postoperative period. We report the case of a 59-year-old man who had undergone ileal neobladder construction 17 months previously. He presented with urinary retention concomitant with urinary tract infection due to a neovesicourethral anastomotic stricture. After a combination of transurethral catheter drainage and broad-spectrum antibiotic therapy for 3 weeks, the fistulous tract completely closed. Therefore, conservative treatment may be regarded as a valid option for a delayed neovesicocutaneous fistula.