A minimal cage of a diamond twin with chirality.

A network of tetrahedral vertices can fill three-dimensional (3D) spaces in a beautiful and isotropic manner, which is found as diamonds with sp3-hybridized carbon atoms. Although a network of trigonal vertices (i.e., another form of carbon atoms with sp2-hybridization) naturally results in a lower-dimensional two-dimensional network of graphenes, an isotropic 3D arrangement of trigonal vertices has been of theoretical and mathematical interest, which has materialized as a proposal of a "diamond twin." We herein report the synthesis and optical resolution of a minimal cage of a chiral diamond-twin network. With triangular phenine units at 14 vertices, triply fused decagonal rings were assembled by forming 15 biaryl edges via coupling. A unique chirality of the network has been disclosed with the minimal cage, which may stimulate explorations of chiral carbonaceous materials.

Bayesian Inference for Model Analyses of Supramolecular Complexes: A Case Study with Nanocarbon Hosts.

A 126 π-electron nanobowl molecule, phenine tridehydrosumanene, was synthesized in 12 steps through the development of a polygon cyclization strategy that assembled the polygonal precursors by Ni-mediated macrocyclization. The bowl-shaped structure accommodated C70 as a guest at the concave site, and the ball-in-bowl structure was determined by X-ray crystallography. The host-guest equilibrium in solution was studied with titration experiments using isothermal calorimetry, which provided an interesting test case for studying the host-guest stoichiometry. Bayesian inference was introduced for stoichiometric analyses of the equilibrium, and a procedure to estimate the volume of prior probability in the parameter space was developed. The Bayesian procedure functioned as Occam's razor and provided quantitative support for a specific stoichiometry. The method was examined with five host-guest examples comprising nanocarbon hosts, which suggested the versatility of Bayesian inference for studies of supramolecular complexes.

Exfoliatable Layered 2D Honeycomb Crystals of Host-guest Complexes Networked by CH-π Hydrogen Bonds.

Studies of graphene show that robust chemical bonds such as covalent bonds with trigonal-planar atoms afford layered atomic 2D crystals possessing unique properties. Although layered molecular crystals are of interest to diversify elements and structures of 2D materials, the structural diversity of molecules as well as weak intermolecular interactions inevitably makes the design to be one-off and individual. We herein report a versatile method to assemble layered molecular crystals. By developing a D3-symmetry host at vertices to form a honeycomb layer, a diverse range of layered 2D host-guest crystals were obtained. Substituents on the host, elements/structures of the guest, the stereochemistry of the host and types of intercalants were diversified, which should allow for 6×32×3×2 combinations for structural diversification.

Introduction of peripheral nitrogen atoms to cyclo-meta-phenylenes.

Cyclo-meta-phenylenes doped with nitrogen atoms at the periphery were designed and synthesized. The syntheses of the macrocyclic structures were achieved with one-pot Suzuki-Miyaura coupling to arrange phenylene rings and pyridinylene rings in an alternating fashion. Analyses with UV-vis spectroscopy showed changes in the photophysical properties with nitrogen doping, and X-ray crystallographic analyses experimentally revealed the presence of biased charges on the peripheral nitrogen atoms.

Akaike's Information Criterion for Stoichiometry Inference of Supramolecular Complexes.

"How do we decide the stoichiometry of host-guest complexes?" This question has long been answered by the Job plot since its first report in 1928. However, as the Job plot was claimed to be misleading in 2016, the question became an open question again and called for renewed investigations. An information-theoretic approach, called Akaike's information criterion, is introduced in this study to select the best model of host-guest complexes, which can rank the models with weight of evidence. A few test cases with unique cylindrical hosts were examined to demonstrate the applicability of the information-theoretic method. Consequently, reasonable views over the thermodynamic behaviors of dumbbell-and-cylinder complexes were obtained. Akaike's information criterion can be a useful and superior alternative to statistical null hypothesis testing, which was proposed as a remedy in place of the Job plot.

Sufficient cardiac unloading by Impella 5.0 in left ventricular rupture following mitral valve replacement: a case report.

A 72-year-old woman presented with exertional dyspnea. Echocardiography revealed severe mitral valve stenosis; therefore, mitral valve replacement was performed using a bioprosthetic valve. However, left ventricular wall rupture occurred following mitral valve replacement. Under re-cardiac arrest, we found a left ventricular tear under the posterior annulus of the mitral valve. We repaired the left ventricular muscle using a bovine pericardial patch and implanted a bioprosthetic valve again. Postoperatively, we implanted an Impella 5.0 heart pump through the right axillary artery to ensure left ventricular wall unloading. Systemic blood flow depended almost completely on mechanical circulatory assistance until postoperative day 3. After the fourth postoperative day, we started weaning the patient from Impella 5.0. Finally, it was completely discontinued on the sixth postoperative day. After that, the patient's condition was stable, and she was discharged 44 days postoperatively. Impella 5.0 is a potentially beneficial device for left ventricular unloading in patients with left ventricular wall rupture following mitral valve replacement.

Phenine design for nanocarbon molecules.

With the name "phenine" given to 1,3,5-trisubstituted benzene for a fundamental trigonal planar unit to weave nanometer-sized networks, a series of curved nanocarbon molecules have been designed and synthesized. Since the 6π-phenine units were amenable to modern biaryl coupling reactions mediated by transition metals, concise syntheses of >400π-nanocarbon molecules were readily achieved. In addition, the phenine design allowed for installing of heteroatoms and/or transition metals doped at specific positions of the large π-systems of the nanocarbon molecules. Fundamental tools were also developed to specify and describe the locations of defects/dopants, quantify pyramidalizations of trigonal panels and estimate molecular Gauss curvatures of the discrete surface. Unique features of phenine nanocarbons, such as stereoisomerism, entropy-driven molecular assembly and effects of dopants on electronic/magnetic characteristics, were revealed during the first half-decade of investigations.

Synthesis of a Negatively Curved Nanocarbon Molecule with an Octagonal Omphalos via Design-of-Experiments Optimizations Supplemented by Machine Learning.

A saddle-shaped nanocarbon molecule was synthesized, which revealed the existence of negative Gauss curvatures on a >3-nm molecular structure possessing 192 π-electrons. The synthesis was facilitated by a protocol developed with Design-of-Experiments optimizations and machine-learning predictions, and spectroscopy and crystallography were used to reveal the saddle-shaped structure of the molecule. Solution-phase analyses showed the presence of dimeric assembly, and crystallographic analyses revealed the stacked dimeric structures. The stacked crystal structure was scrutinized by various methods, including Gauss curvatures derived from the discrete surface theory of geometry, to reveal the important role of the molecular Gauss curvature in dimeric assembly.

A Defective Nanotube Molecule of C552 H496 N24 with Pyridinic and Pyrrolic Nitrogen Atoms.

A 3-nm molecule comprising a cylindrical core and cross-shaped rims was designed and synthesized by developing a modular synthetic route. By using a cyclic precursor from previous studies as a starting material, multiple carbazole units were installed at the rims of the defective cylinder. The defective cylinder was synthetically doped with two types of nitrogen atoms, that is, pyridinic and pyrrolic nitrogen atoms, which resulted in solvatochromic shifts in fluorescence by charge-transfer interactions. The structure of the large, C552 H496 N24 molecule was fully disclosed by crystallographic analyses, and the unique helical arrangement of nitrogen-doped cylinders in the crystal was revealed.

Metal-Templated Oligomeric Macrocyclization via Coupling for Metal-Doped π-Systems.

A method for the synthesis of metal-doped aromatic macrocycles has been developed. The method, i.e., metal-templated oligomeric macrocyclization via coupling, adopts Ni as the template and assembles five pyridine units via a Ni-mediated coupling reaction to form aryl-aryl linkages. A pentameric oligopyridyl macrocycle was selectively obtained in good yield, and the reaction was also applicable to a gram-scale synthesis. The pentameric oligopyridyl macrocycle captured d8-Ni(II) at the center to form a paramagnetic pentagonal-bipyramidal complex. The method was applied to the synthesis of a large π-molecule to afford a nanometer-sized, bowl-shaped molecule having a unique combination of 120π and 8d electrons.

Chemical Reduction of a Nanosized [6]Cyclo-2,7-naphthylene Macrocycle.

Chemical reduction of a naphthylene macrocycle, [6]cyclo-2,7-naphthylene ([6]CNAP, 1), with alkali metals, Li and K, revealed the accessibility of the doubly-reduced state of 1. The macrocyclic 12- anion was isolated in different coordination environments and crystallographically characterized. The single-crystal X-ray diffraction confirmed the formation of contact-ion complexes with one Li+ and two K+ ions in THF, and a "naked" dianion in the solvent-separated ion product with K+ ions in the presence of 18-crown-6 ether. The detailed structural analysis of 12- showed that the π-conjugation over the biaryl linkages between naphthylene panels were enhanced upon two-fold reduction, which was rationally explained by theoretical calculations.

Fluorescence Enhancement of Aromatic Macrocycles by Lowering Excited Singlet State Energies.

A series of cyclo-meta-phenylene congeners with a variation of interphenylene bridges was synthesized by adopting concise synthetic routes to investigate the structure-fluorescence relationships of macrocycles. With fundamental UV-vis absorption and fluorescence spectra, no unique effect of the macrocyclic structures was noted. However, the fluorescence quantum yields were dramatically affected by the macrocyclic structures and varied at a range of 5-92%. The quantum yields qualitatively depended on the number of the vinylene-bridged phenanthrenylene panels, and the theoretical investigations revealed the energetic and structural effects of the phenanthrenylene panels during nanosecond photodynamic processes. A high energy barrier along the S0/S1 internal conversion path to reach the minimum energy conical intersection was necessary to hamper a nonradiative process, and with the transition state energy level of the excited singlet state being insensitive to macrocyclic structures, a low energy level of excited singlet states (S1MIN) was required to facilitate efficient fluorescence.

Synthesis of a Hemispherical Geodesic Phenine Framework by a Polygon Assembling Strategy.

A synthetic strategy to construct large geodesic structures of phenine (1,3,5-trisubstituted benzene) was devised. In this strategy, five pentagons were assembled on an omphalos pentagon, and bridging peripheral pentagons furnished five additional hexagons. Thirty phenine units were synthetically assembled to afford a large C220 H180 molecule with a phenine framework isoreticular to a hemispherical, bisected segment of C60 . Although a hemispherical structure of the phenine framework was suggested by solution-phase NMR spectra, crystallographic analysis revealed an oval-like deformation of the molecular shape. In-depth structural analyses, including theoretical calculations, showed that structural fluctuations observed as variations in the biaryl torsion angles allowed structural deformations and, at the same time, that the dynamic fluctuations resulted in the spectroscopic observation of a hemisphere as a time-averaged structure.

Synthesis, Structures, and Assembly of Geodesic Phenine Frameworks with Isoreticular Networks of [ n]Cyclo- para-phenylenes.

A series of macrocycles were designed by rendering geodesic phenine frameworks in isoreticular networks of [ n]cyclo- para-phenylenes. Large, nanometer-sized molecules exceeding molecular weights of 2000 Da were synthesized by five-step transformations including macrocyclization of [6]cyclo- meta-phenylene panels. The dependence of both the molecular structures and the fundamental properties on the panel numbers was delineated by a combination of spectroscopic and crystallographic analyses with the aid of theoretical calculations. Interestingly, flexibility of the molecules via panel rotations depends on the hoop size, which has not been disclosed with the small isoreticular [ n]cylco- para-phenylenes. One of the macrocycles served as a host for C70, and its association behaviors and crystal structures were revealed.

Fluctuating Carbonaceous Networks with a Persistent Molecular Shape: A Saddle-Shaped Geodesic Framework of 1,3,5-Trisubstituted Benzene (Phenine).

A saddle-shaped macromolecule has been synthesized. The molecule was designed as a geodesic saddle with 1,3,5-trisubstituted benzene (named phenine) as the fundamental unit. The phenines were woven into a polygonal framework that was composed of 168 sp2 -hybridized carbon atoms. The saddle-shaped structure with unique symmetry showed atypical conformational changes. The biaryl linkages in this molecule had a small energy barrier for rotation, and these structural fluctuations resulted in seven 1 H NMR resonances representing 84 aromatic hydrogen atoms. Nevertheless, the overall saddle shape of the molecule was persistent, and the "up" and "down" orientations of phenine moieties circulated to give average 1 H resonances. The structural characteristics of this molecule, including the anomalous entropy-driven dimerization, may deepen our understanding of defect-rich graphitic sheets.

Synthesis and Bowl-in-Bowl Assembly of a Geodesic Phenylene Bowl.

A phenylene multiring with a corannulenoidal skeleton was synthesized. Geodesic constraints over 20 phenylene panels resulted in its nanometer-sized, bowl-shaped molecular structure, which was unequivocally revealed by crystallographic analysis. The crystal structure also showed the presence of a bowl-in-bowl dimeric assembly, which was driven by entropic factors in solution.

Modular Synthesis of Aromatic Hydrocarbon Macrocycles for Simplified, Single-Layer Organic Light-Emitting Devices.

A method for the modular synthesis of aromatic hydrocarbon macrocycles has been developed for base materials in single-layer organic light-emitting devices. The method with Ir-catalyzed direct C-H borylation and Suzuki-Miyaura coupling was concise and scalable, which allowed for a gram-scale preparation of aromatic hydrocarbon macrocycles that have bulky substituents at the periphery. The new arylated hydrocarbon macrocycles enabled a quantitative electro-optical conversion in organic light-emitting devices with a phosphorescent emitter, which is, notably, in a single-layer architecture consisting of two regions of doped and undoped materials. The highest external quantum efficiencies reached 24.8%, surpassing those of previous hydrocarbon base materials.

Networked-cage microcrystals for evaluation of host-guest interactions.

We have developed a new synthetic protocol for the preparation of a microcrystalline powder (median size: X50 = 25 µm) of networked M6L4 cages 1a for the stationary phase of an affinity column on a greater than 50 g scale. Analogously to large single crystals 1b (X50 ≈ 0.5 mm), microcrystals 1a accommodate guest molecules tetrathiafulvalene (TTF) and fullerene (C60) at up to 32 and 35 wt %, respectively. Importantly, the host-guest interactions within networked cages could be evaluated in terms of the retention time from HPLC analysis by using microcrystals 1a as the stationary phase. In this way, favorable guests for networked cages 1 and even solution M6L4 cage 2 could easily be assessed by HPLC.

X-ray snapshot observation of palladium-mediated aromatic bromination in a porous complex.

Pd-mediated aromatic bromination is intriguing to synthetic and organometallic chemists due to both its synthetic utility and, more importantly, a proposed mechanism involving an uncommon Pd(IV)/Pd(II) catalytic cycle. Here, we report an X-ray snapshot observation of a Pd reaction center during a Pd-mediated aromatic bromination in a single crystal of a porous coordination network crystalline scaffold. Upon treatment of a single crystal with N-bromosuccinimide, sequential X-ray snapshots revealed that the aryl-Pd(II)-L species embedded in the network pores was converted to the brominated aryl product through a transient aryl-Pd(II)-Br species, which is normally unobservable because of its rapid dimerization into insoluble Pd2(µ-Br)2 species. Though the reaction pathway may be biased by the crystalline state, the new X-ray snapshot method relies on crystalline flasks to provide important mechanistic insight.

Cyclo-meta-phenylene revisited: nickel-mediated synthesis, molecular structures, and device applications.

From a one-pot nickel-mediated Yamamoto-type coupling reaction of m-dibromobenzene, five congeners of [n]cyclo-meta-phenylenes were synthesized and fully characterized. The [n]cyclo-meta-phenylenes possessed a commonly shared arylene unit and intermolecular contacts but varied in packing structures in the crystalline solid state. Columnar assembly of larger congeners yielded nanoporous crystals with carbonaceous walls to capture minor protic or aliphatic solvent molecules. The concise and scalable synthesis allowed exploration of the macrocyclic hydrocarbons as bipolar charge carrier transport materials in organic light-emitting diode devices.