Search

Boron and boron-based nanoclusters exhibit unique structural and bonding patterns in chemistry. Extensive density functional theory calculations performed in this work predict the mononuclear walnut-like Ci C50B54 (1) (C2B10@C48B44), C1 C50B54 (2) (CB11@C49B43), and S10 C50B54 (3) (B12@C50B42) which contain one icosahedral-CnB12-n core (n = 0, 1, 2) at the center following the Wade’s skeletal electron counting rules and the approximately electron sufficient binuclear peanut-like Cs C88B78 (4) ((C2B10)2@C84B58), Cs C88B78 (5) ((CB11)2@C86B56), Cs C88B78 (6) ((B12)2@C88B54), Cs B180 (7) ((B12)2@B156), Cs B182 (8) ((B12)2@B158), and Cs B184 (9) ((B12)2@B160) which encapsulate two interconnected CnB12-n icosahedrons inside. These novel core-shell borafullerene and borospherene nanoclusters appear to be the most stable species in thermodynamics in the corresponding cluster size ranges reported to date. Detailed bonding analyses indicate that the icosahedral B122-, CB11-, and C2B10 cores in these core-shell structures possess the superatomic electronic configuration of 1S21P61D101F8, rendering spherical aromaticity and extra stability to the systems. Such superatomic icosahedral-CnB12-n stuffed borafullerenes and borospherenes with spherical aromaticity may serve as embryos to form bulk boron allotropes and their carbon-boron binary counterparts in bottom-up approaches.

Boron and boron-based nanoclusters exhibit unique structural and bonding patterns in chemistry. Extensive density functional theory calculations performed in this work predict the mononuclear walnut-like C

Boron allotropes are known to be predominately constructed by icosahedral B12 cages, while icosahedral-B12 stuffing proves to effectively improve the stability of fullerene-like boron nanoclusters in the size range between B98–B102. However, the thermodynamically most stable core-shell borospherenes with a B12 icosahedron at the center still remains unknown. Based on the structural motif of D5h C70 and extensive first-principles theory calculations, we predict herein the high-symmetry C5v B111+ (3) which satisfies the Wade’s n+1 and n+2 skeletal electron counting rules exactly and the approximately electron sufficient Cs B111 (4), Cs B112 (5), Cs B113 (6), and Cs B114 (7) which are the most stable neutral core-shell borospherenes with a B12 icosahedron at the center reported to date in the size range between B68–B130, with Cs B112 (5) being the thermodynamically most favorite species in the series. Detailed orbital and bonding analyses indicate that these spherically aromatic species all contain a negatively charged icosahedral B122− core at the center which exhibits typical superatomic behaviors in the electronic configuration of 1S21P61D101F8, with its dangling valences saturated by twelve radial B-B 2c-2e σ bonds between the B12 inner core and the B70 outer shell. The infrared (IR) and Raman spectra of the concerned species are computationally simulated to facilitate their future characterizations.

Despite its electron deficiency, boron can form multiple bonds with a variety of elements. However, multiple bonds between boron and main-group metal elements are relatively rare. Here we report the observation of boron-lead multiple bonds in PbB2O– and PbB3O2–, which are produced and characterized in a cluster beam. PbB2O– is found to have an open-shell linear structure, in which the bond order of B☱Pb is 2.5, while the closed-shell [Pb≡B–B≡O]2– contains a B≡Pb triple bond. PbB3O2– is shown to have a Y-shaped structure with a terminal B = Pb double bond coordinated by two boronyl ligands. Comparison between [Pb≡B–B≡O]2–/[Pb=B(B≡O)2]– and the isoelectronic [Pb≡B–C≡O]–/[Pb=B(C≡O)2]+ carbonyl counterparts further reveals transition-metal-like behaviors for the central B atoms. Additional theoretical studies show that Ge and Sn can form similar boron species as Pb, suggesting the possibilities to synthesize new compounds containing multiple boron bonds with heavy group-14 elements.

Since the discovery of the cage-like borospherenes D2d B40−/0 and the first axially chiral borospherenes C3/C2 B39−, a series of fullerene-like boron clusters in different charge states have been reported in theory. Based on extensive global minimum searches and first-principles theory calculations, we present herein two new axially chiral members C2 B31+ (I) and C2 B32 (VI) to the borospherene family. B31+ (I) features two equivalent heptagons on the top and one octagon at the bottom on the cage surface, while B32 (VI) possesses two equivalent heptagons on top and two equivalent heptagons at the bottom. Detailed bonding analyses show that both sea-shell-like B31+ (I) and B32 (VI) follow the universal σ + π double delocalization bonding pattern of the borospherene family, with ten delocalized π bonds over a σ skeleton, rendering spherical aromaticity to the systems. Extensive molecular dynamics simulations show that these novel borospherenes are kinetically stable below 1000 K. The IR, Raman, and UV-vis spectra of B31+ (I) and B32 (VI) are computationally simulated to facilitate their future experimental characterizations.

The newly discovered cage-like borospherene D2d B40 with two η6-B6 hexagons and four η7-B7 heptagons on the surface may serve as an effective multi-dentate ligand to coordinate transition metals. Based upon extensive density functional theory calculations, we present herein the possibility of the exohedral complex series (C6H6Cr)n&B40 (n = 1–6) with n Cr centres sandwiched between the central η6/7-B40 unit and n planar η6-C6H6 ligands. C6H6Cr fragments in (C6H6Cr)n&B40 occupy the η6-B6 hexagonal coordination site atop the B40 cage first, the four neighboring η7-B7 heptagons on the waist next, and finally the η6-B6 hexagon at the bottom, forming a multinuclear complex series effectively stabilized by n C6H6Cr fragments. The two η6-B6 hexagons and four η7-B7 heptagons on the spherical surface of B40 can be practically viewed as six independent coordination sites to coordinate Cr centers with almost the same coordination energies. Detailed bonding analyses indicate that the eclipsed C2v C6H6Cr&B40 (1-1) possesses a coordination bonding pattern similar to that of dibenzenechromium, with the B40 ligand inheriting the σ + π double delocalization bonding pattern of the parent borospherene. The IR, Raman, and UV–vis absorption spectra of C2v C6H6Cr&B40 (1-1) are theoretically simulated to facilitate its future experimental characterization.

Inspired by recent discoveries of alkaline-earth octacarbonyls and based on extensive first-principles theory investigations, we predict herein the possibility of perfect cube-like alkali octacarbonyls M(CO) 8 − (Oh, 3A1g) (1) (M = K, Rb) which satisfy the 18-electron rule in an octacoordinate cubic field with (n − 1)d-orbital participation of alkali metal center playing an important role in M–CO coordination interaction. The slightly elongated neutral M(CO)8 (D4h, 2B1g) (3) turn out to be similar with the experimentally observed Ba(CO) 8 + monocation in an octacoordinate tetragonal field. Detailed orbital analyses indicate that, similar to neutral alkaline-earth octacarbonyls, M(CO) 8 − monoanions possess the superatomic electronic configuration of S2P6D8F2, with the alkali–CO coordination interaction mainly originating from M(dπ) → (CO)8(π*) backdonations which result in strong red shifts of the C–O stretching frequencies relative to free CO.

The highest coordination number identified to date in planar species is CN = 10 in metal-centered monocyclic boron wheel clusters D10h M©B10− (M = Ta and Nb) (Galeev et. al., Angew. Chem. Int. Ed., 2012, 51, 2101). Extensive global minimum searches and first-principles theory calculations performed herein indicate that the experimentally observed LaC13+ and LaC14+ possess the well-defined global minima of perfect metal-centered monocyclic carbon wheel D13h La©C13+ (1) and slightly off-centered C2v La©C14+ (4) (1A1) with record coordination numbers of CN = 13 and 11 in planar structures, respectively, further pushing the boundary of our understanding of chemical structures and bonding. Detailed molecular orbital, nucleus-independent chemical shift, and ring current analyses indicate that D13h La©C13+ (1) is σ + π dually aromatic in nature, with 14 totally delocalized in-plane σ electrons and 14 totally delocalized out-of-plane π electrons each matching the 4N + 2 aromatic rule (Nσ = Nπ = 3). Similar σ + π dually aromatic metal-centered monocyclic wheel clusters D13h Ca©C13 (2), C13v Ac©C13+ (3), C2v Y©B6C6+ (5), and C2v Sc©B5C6 (6) have also been obtained with CN = 13, 13, 12, and 11, respectively. The results obtained in this work effectively enrich the chemical structures and bonding patterns of planar hypercoordinated complexes.

As the first all-boron fullerene observed in experiments, cage-like borospherene B40 has attracted considerable attention in recent years. However, B40 has been proved to be chemically reactive and tends to coalesce with one another via the formation of covalent bonds. We explore herein the possibility of low-dimensional functional networks of B40 with effective transition-metal intercalations. We find that the four equivalent B7 heptagons on the waist of each B40 can serve as effective ligands to coordinate various transition metal centers in exohedral motifs. The intercalated metal atoms entail these networks with a variety of intriguing properties. The two-dimensional (2D) Cr2B40 network is a ferromagnetic metal while the 2D Zn2B40 network becomes semiconducting. In contrast, other 2D M2B40 (M = Sc, Ti, V, Mn, Fe, Co, Ni and Cu) networks and 1D CrB40 belong to nonmagnetic metals. The 3D Cr3B40 network is a magnetic metal. This work presents the viable possibility of assembling Mn&B40 metalloborospherenes into stable functional nanomaterials via effective transition-metal intercalations with potential applications in electronic and spintronic devices.

Carbon and boron can mix to form numerous two-dimensional (2D) compounds with strong covalent bonds, yet very few possess a bandgap for functional applications. Motivated by the structural similarity between graphene and recently synthesized borophene, we propose a new family of semiconducting boron carbide monolayers composed of B4C3 pyramids and carbon hexagons, denoted as (B4C3)m(C6)n (m, n are integers) by means of the global minimum search method augmented with first-principles calculations. These monolayers are isoelectronic to graphene yet exhibit increased bandgaps with decreasing n/m, due to the enhanced localization of boron multicenter bonding states as a consequence of the electronic transfer from boron to carbon. In particular, the B4C3 monolayer is even more stable than the previously synthesized BC3 monolayer and has a direct bandgap of 2.73 eV, with the promise for applications in optical catalysis and optoelectronics. These results are likely to inform the on-going effort on the design of semiconducting 2D materials based on other light elements.

Classic two-dimensional graphene possesses outstanding properties due to Dirac cone structures so that many Dirac cone materials had been predicted. Using the first principle symmetric search algorithm, a new graphene-like carbon allotrope with P2m space group, named azugraphene, was predicted and its 38 atoms in the unit cell can be fragmented into three 5–7 rings of azulene, one hexagon, and two remainder atoms. Azugraphene is a low-energy graphene-like hexagonal carbon allotrope with six Dirac cones in the first Brillouin zone. Due to its stability and the existence of its elementary fragments, azugraphene is potentially synthesizable. In addition, the stable AB stacking bilayer azugraphene is also a Dirac cone material with a band gap of 2.5 meV. Therefore, both the monolayer and bilayer azugraphenes have great potential in physics, chemistry, and nanoelectronics.

Lanthanide-boron binary clusters possess interesting structures and bonding which may provide insights into designing new boride nanomaterials. Inspired by the recently discovered mono-decker inverse sandwich D9h La2B9- (1A'1) (1) and based on the extensive first-principles theory calculations, we predict herein the possible existence of a series of bi-decker inverse sandwich di-lanthanide boron complexes including D9d La2[B18] (3A1g) (2), D9d La2[B18]2- (1A1g) (3), and C2h La2[B2@B18] (1Ag) (4) which all contain a tubular Bn ligand (n = 18, 20) sandwiched by two La atoms at the two ends. In these novel clusters, La2[B2@B18] (4) as a tubular molecular rotor with the smallest core-shell structure reported to date in boron-based nanoclusters possesses a B2-bar rotating constantly and almost freely inside the B18 tube around it at room temperature. Detailed bonding analyses indicate that these complexes are stablized by effective (d-p)σ, (d-p)π, and (d-p)δ coordination interactions between the La centers and Bn bi-decker ligand. Six multi-center fluxional σ-bonds between the B2-core and B18 tube in La2[B2@B18] (4) are found to be responsible for its unique fluxional behaviors. The IR and Raman spectra of the concerned species are simulated to facilitate their experimental characterization.

Since the discovery of the cage-like borospherenes

Recent joint experimental and theoretical investigations have shown that seashell-like C2 B28 is the smallest neutral borospherene reported to date, while seashell-like Cs B29- (1-) as a minor isomer competes with its quasi-planar counterparts in B29- cluster beams. Extensive global minimum searches and first-principles theory calculations performed in this work indicate that with two valence electrons detached from B29-, the B29+ monocation favors a seashell-like Cs B29+ (1+) much different from Cs B29- (1-) in geometry which is overwhelmingly the global minimum of the system with three B7 heptagonal holes in the front, on the back, and at the bottom, respectively, unveiling an interesting charge-induced structural transition from Cs B29- (1-) to Cs B29+ (1+). Detailed bonding analyses show that with one less σ bond than B29- (1-), Cs B29+ (1+) also possesses nine delocalized π-bonds over its σ-skeleton on the cage surface with a σ + π double delocalization bonding pattern and follows the 2(n + 1)2 electron counting rule for 3D spherical aromaticity (n = 2). B29+ (1+) is therefore the smallest borospherene monocation reported to date which is π-isovalent with the smallest neutral borospherene C2 B28. The IR, Raman, and UV-vis spectra of B29+ (1+) are computationally simulated to facilitate its spectroscopic characterization.

Shortly after the discovery of all-boron fullerenes D2d B40−/0 (borospherenes), the first axially chiral borospherenes C3/C2 B39− were characterized in experiments in 2015. Based on extensive global minimum searches and first-principles theory calculations, we present herein two new axially chiral members to the borospherene family: the aromatic cage-like C2 B34(1) and C2 B35+(2). Both B34(1) and B35+(2) feature one B21 boron triple chain on the waist and two equivalent heptagons and hexagons on the cage surface, with the latter being obtained by the addition of B+ into the former at the tetracoordinate defect site. Detailed bonding analyses show that they follow the universal bonding pattern of σ + π double delocalization, with 11 delocalized π bonds over a σ skeleton. Extensive molecular dynamics simulations show that these borospherenes are kinetically stable below 1000 K and start to fluctuate at 1200 K and 1100 K, respectively. The IR, Raman, and UV-vis spectra of 1 and 2 are computationally simulated to facilitate their experimental characterization.

Transition-metal doping leads to dramatic structural changes and results in novel bonding patterns in small boron clusters. Based on the experimentally derived mono-ring planar C9v Ta©B92- (1) and extensive first-principles theory calculations, we present herein the possibility of high-symmetry double-ring tubular D9d Ta@B183- (2) and C9v Ta2@B18 (3) and triple-ring tubular D9h Ta2@B27+ (4), which may serve as embryos of single-walled metalloboronanotube α-Ta3@B48(3,0) (5) wrapped up from the recently observed most stable free-standing boron α-sheet on a Ag(111) substrate with a transition-metal wire (-Ta-Ta-) coordinated inside. Detailed bonding analyses indicate that, with an effective dz2-dz2 overlap on the Ta-Ta dimer along the C9 molecular axis, both Ta2@B18 (3) and Ta2@B27+ (4) follow the universal bonding pattern of σ + π double delocalization with each Ta center conforming to the 18-electron rule, providing tubular aromaticity to these Ta-doped boron complexes with magnetically induced ring currents. The IR, Raman, and UV-vis spectra of 3 and 4 are computationally simulated to facilitate their future experimental characterization.

Protonated water cluster is one of the most important hydrogen-bond network systems. Finding an appropriate DFT method to study the properties of protonated water clusters can substantially improve the economy in computational resources without sacrificing the accuracy compared to high-level methods. Using high-level MP2 and CCSD(T) methods as well as experimental results as benchmark, we systematically examined the effect of seven exchange-correlation GGA functionals (with BLYP, B3LYP, X3LYP, PBE0, PBE1W, M05-2X, and B97-D parametrizations) in describing the geometric parameters, interaction energies, dipole moments, and vibrational properties of protonated water clusters H+(H2O)2–9,12. The overall performance of all these functionals is acceptable, and each of them has its advantage in certain aspects. X3LYP is the best to describe the interaction energies, and PBE0 and M05-2X are also recommended to investigate interaction energies. PBE0 gives the best anharmonic frequencies, followed by PBE1W, B97-D a...

As the first all-boron fullerene observed in experiments, cage-like borospherene B40 has attracted considerable attention in recent years. However, B40 has been proved to be chemically reactive and tends to coalesce with one another via the formation of covalent bonds. We explore herein the possibility of low-dimensional functional networks of B40 with effective transition-metal intercalations. We find that the four equivalent B7 heptagons on the waist of each B40 can serve as effective ligands to coordinate various transition metal centers in exohedral motifs. The intercalated metal atoms entail these networks with a variety of intriguing properties. The two-dimensional (2D) Cr2B40 network is a ferromagnetic metal while the 2D Zn2B40 network becomes semiconducting. In contrast, other 2D M2B40 (M = Sc, Ti, V, Mn, Fe, Co, Ni and Cu) networks and 1D CrB40 belong to nonmagnetic metals. The 3D Cr3B40 network is a magnetic metal. This work presents the viable possibility of assembling MnB40 metalloborospherenes into stable functional nanomaterials via effective transition-metal intercalations with potential applications in electronic and spintronic devices.

Inspired by the recent discovery of the metal-centered tubular molecular rotor Cs B2-Ta@B18− with the record coordination number of CN = 20 and based on extensive first-principles theory calculations, we present herein the possibility of the largest tubular molecular rotors Cs B3-Ta@B18 (1) and C3v B4-Ta@B18+ (2) and smallest axially chiral endohedral metalloborospherenes D2 Ta@B22− (3 and 3′), unveiling a tubular-to-cage-like structural transition in metal-centered boron clusters at Ta@B22−via effective spherical coordination interactions. The highly stable Ta@B22− (3) as an elegant superatom, which features two equivalent corner-sharing B10 boron double chains interconnected by two B2 units with four equivalent B7 heptagons evenly distributed on the cage surface, conforms to the 18-electron configuration with a bonding pattern of σ + π double delocalization and follows the 2(n + 1)2 electron counting rule for spherical aromaticity (n = 2). Its calculated adiabatic detachment energy of ADE = 3.88 eV represents the electron affinity of the cage-like neutral D2 Ta@B22 which can be viewed as a superhalogen. The infrared, Raman, VCD, and UV-vis spectra of the concerned species are computationally simulated to facilitate their spectral characterizations.

The recently observed cage-like borospherenes D2d B40−/0 and C3/C2 B39− have attracted considerable attention in chemistry and materials science. Based on extensive global minimum searches and first-principles theory calculations, we present herein the possibility of cage-like Cs B39+ (1) and Cs B39+ (2) which possess five hexagonal and heptagonal faces and one filled hexagon and follow the bonding pattern of σ + π double delocalization with 12 delocalized π bonds over a σ-skeleton, adding two new members to the borospherene family. IR, Raman, and UV-vis spectra of Cs B39+ (1) and Cs B39+ (2) are computationally simulated to facilitate their experimental characterization.

Based on extensive global searches and first-principles theory calculations, we present herein the possibility of double-ring tubular (B2O2)n clusters (n = 6–42) (2–10) rolled up from the most stable one-dimensional (1D) BO double-chain ribbon (1) in boron monoxides. Tubular (3D) (B2O2)n clusters (n ≥ 6) are found to be systematically much more stable than their previously proposed planar (2D) counterparts, with a 2D–3D structural transition at B12O12 (2). Detailed bonding analyses on 3D (B2O2)n clusters (2–10) and their precursor 1D BO double-chain ribbon (1) reveal two delocalized B–O–B 3c-2e π bonds over each edge-sharing B4O2 hexagonal unit which form a unique 6c-4e o-bond to help stabilize the systems. The IR, Raman, UV-vis, and photoelectron spectra of the concerned species are computationally simulated to facilitate their experimental characterization.

Detailed molecular orbital and bonding analyses reveal the existence of both fluxional σ- and π-bonds in the global minima C

Transition-metal doping leads to dramatic structural changes and results in novel bonding patterns in small boron clusters. Based on the experimentally derived mono-ring planar C9v Ta©B92- (1) and extensive first-principles theory calculations, we present herein the possibility of high-symmetry double-ring tubular D9d Ta@B183- (2) and C9v Ta2@B18 (3) and triple-ring tubular D9h Ta2@B27+ (4), which may serve as embryos of single-walled metalloboronanotube α-Ta3@B48(3,0) (5) wrapped up from the recently observed most stable free-standing boron α-sheet on a Ag(111) substrate with a transition-metal wire (-Ta-Ta-) coordinated inside. Detailed bonding analyses indicate that, with an effective dz2-dz2 overlap on the Ta-Ta dimer along the C9 molecular axis, both Ta2@B18 (3) and Ta2@B27+ (4) follow the universal bonding pattern of σ + π double delocalization with each Ta center conforming to the 18-electron rule, providing tubular aromaticity to these Ta-doped boron complexes with magnetically induced ring currents. The IR, Raman, and UV-vis spectra of 3 and 4 are computationally simulated to facilitate their future experimental characterization.

Based on detailed bonding analyses on the fluxional behaviors of planar B

Based on extensive first-principles theory calculations, we present the possibility of an endohedral charge-transfer complex, Cs Ca@B37(-) (), which contains a 3D aromatic fullerene-like Cs B37(3-) () trianion composed of interwoven boron double chains with twelve delocalized multicenter π bonds (12 mc-2e π, m = 5, 6) over a σ skeleton, completing the Bn(q) borospherene family (q = n - 40) in the size range of n = 36-42.

The selective in situ reactions of 1,2-di(1H-benzimidazol-2-yl)ethane-1,2-diol (TDB) in the presence of 3d transition-metal ions under hydrothermal conditions were investigated. The research demonstrated that divalent Fe, Co, and Ni salts are apt to cause the intramolecular dehydration of TDB, then form pentanuclear [M5(H2L)6]4+ clusters, and Cu cations tend to activate specific C–C bonds, then give rise to benzimidazole derivatives and the corresponding copper(I/II) complexes. The results illuminate that reaction temperature and pressure are necessary conditions for molecular rearrangement and the radii and valence state of metal ions are key factors in the metal-responsive decomposition of TDB. Based on the results, the corresponding mechanism is proposed. Moreover, the synthesis, crystal structure, thermal stability and magnetism of related complexes are investigated.

Based on extensive first-principles theory calculations, we present the possibility of construction of the Saturn-like charge-transfer complexes Li4&B36 (2), Li5&B36+ (3), and Li6&B362+ (4) all of which contain a perfect cage-like B364− (1) core composed of twelve interwoven boron double chains with a σ + π double delocalization bonding pattern, extending the Bnq borospherene family from n = 38–42 to n = 36 with the highest symmetry of Th.

The double-chain boron ribbon should be taken as an element geometric unit for the construction of boron fullerenes and sheets. In this work, a series of B2n C2H2 clusters (n = 2–9) were extensively investigated using the density functional theory and the coupled cluster method. The most stable structures of B2n C2H2 are planar double-chain nanoribbon with lengths from 3.9 to 15.0 A. The adaptive natural density partitioning analyses show that there exist conjugated multi-center π bonds along the nanoribbons. The two-dimensional contour pictures of the nucleus-independent chemical shifts reveal that B2n C2H2 clusters have ribbon aromaticity that fluctuates along the ribbons. This finding will provide new insights on the boron fullerenes and the two-dimensional boron sheets.

The newly discovered borospherenes B40 (-/0) and B39 (-) mark the onset of a new class of boron nanostructures. Based on extensive first-principles calculations, we introduce herein two new chiral members to the borospherene family: the cage-like C1 B41 (+) (1) and C2 B42 (2+) (2), both of which are the global minima of the systems with degenerate enantiomers. These chiral borospherene cations are composed of twelve interwoven boron double chains with six hexagonal and heptagonal faces and may be viewed as the cuborenes analogous to cubane (C8 H8 ). Chemical bonding analyses show that there exists a three-center two-electron σ bond on each B3 triangle and twelve multicenter two-electron π bonds over the σ skeleton. Molecular dynamics simulations indicate that C1 B41 (+) (1) fluctuates above 300 K, whereas C2 B42 (2+) (2) remains dynamically stable. The infrared and Raman spectra of these borospherene cations are predicted to facilitate their experimental characterizations.

Background: Adventitial fibroblasts have been shown to play an important role in vascular remodeling and contribute to neointimal formation in vascular diseases. However, little is known about adventitial fibroblast subpopulations. This study explored the process of isolating rat thoracic aorta adventitial fibroblast subpopulations and characterized their properties following stimulation with angiotensin II (ANG II), a critical factor involved in cardiovascular diseases such as hypertension. Methods: Adventitial fibroblasts were isolated and cultured from rat aorta. Fibroblast subpopulations were individually expanded using cloning ring techniques. Cells were treated with ANG II (10 nM, 100 nM and 1 μM) for 0.5, 1, 1.5, 3, 6, 12, or 24 h, and ANG II-induced proliferation and migration were measured by MTT assay and Transwell. Cells were treated with ANG II (100 nM) in the presence or absence of ANG II receptor antagonists (100 μM), losartan (for AT1) and PD-123319 (for AT2). PreproET-1 mRNA and ET-1 were determined by RT-PCR and ELISA, respectively. Collagen type I was detected by western blotting. Results: Two major fibroblast subpopulations were found in the adventitia, epithelioid-like cells and spindle-like cells; Although ANG II promotes the growth of both subpopulations, epithelioid-like cell proliferation shows dose-dependency on ANG II from 10 nM to 1 μM, while proliferation of spindle-like cells reaches a peak value following 100 nM ANG II stimulation; ANG II stimulation enhanced epithelioid-like but not spindle-like cell migration; ANG II dose-dependently increased the expression of preproET-1 and collagen type I, and enhanced ET-1 secretion in epithelioid-like but not spindle-like cells, effects abolished by the AT1 receptor antagonist, but not with AT2 receptor antagonist. Conclusion: Adventitial fibroblasts are heterogeneous and epithelioid-like subpopulations with high sensitivity to ANG II stimulation may be implicated in the pathophysiological mechanisms of vascular remodeling, reparative processes and cardiovascular diseases.

MoP is a promising catalyst in heterogeneous catalysis. Understanding its surface stability and morphology is the first and essential step in exploring its catalytic properties. However, traditional surface energy calculation method does not work for the asymmetric termination of MoP. In this work, we reported a useful DFT based method to get the surface energies of asymmetric MoP facets. Under ideal condition, the (101) surface with mixed Mo/P termination is most stable, followed by the (100) surface, while the (001) surface is least stable. Wulff construction reveals the exposure of six surfaces on the MoP nanoparticle, where the (101) has the largest contribution. Atomistic thermodynamics results reveal the changes in surface stability orders with experimental conditions, and the (001)-P termination becomes more and more stable with increasing P chemical potential, which indicates its exposure is possible at defined conditions. Our results agree well with the previous experimental XRD and TEM data. We believe the reported method for surface energy calculation could be extended to other similar systems with asymmetric surface terminations.

The Dirac point and cones make some two-dimensional materials (e.g., graphene, silicone and graphyne) exhibit ballistic charge transport and enormously high carrier mobilities. Here, we present a novel semimetal with triangular lattice. Metallic BeB2 monolayer could transform to a semimetal with a Dirac point at the Fermi level when the lattice parameters are isotropically compressed by about 5%, while it becomes metallic again under larger compression. The Fermi velocity of semimetallic BeB2 monolayer is 0.857 × 106 m s−1, just a little smaller than that of graphene. Furthermore, it is found that uniaxial compressive strain opens a band gap in the BeB2 monolayer, while uniaxial tensile strain keeps it metallic. Our study expands the Dirac systems and provides new insight to explore novel semimetallic materials.

Inspired by the recent discovery of the metal-centered tubular molecular rotor C

Based on extensive global searches and first-principles theory calculations, we present herein the possibility of double-ring tubular (B

With inspirations from recent discoveries of the cage-like borospherene B40 and perfectly planar Co ∈ B18− and based on extensive global minimum searches and first-principles theory calculations, we present herein the possibility of the novel planar Ni ∈ B18 (1), cage-like heteroborospherenes Nin ∈ B40 (n = 1–4) (2–5), and planar heteroborophenes Ni2 ∈ B14 (6, 7) which all contain planar or quasi-planar heptacoordinate transition-metal (phTM) centers in η7-B7 heptagons. The nearly degenerate Ni2 ∈ B14 (6) and Ni2 ∈ B14 (7) monolayers are predicted to be metallic in nature, with Ni2 ∈ B14 (6) composed of interwoven boron double chains with two phNi centers per unit cell being the precursor of cage-like Nin ∈ B40 (n = 1–4) (2–5). Detailed bonding analyses indicate that Nin ∈ B40 (n = 1–4) (2–5) and Ni2 ∈ B14 (6, 7) possess the universal bonding pattern of σ + π double delocalization on the boron frameworks, with each phNi forming three lone pairs in radial direction (3dz22, 3dzx2, and 3dyz2) and two effective nearly in-plane 8c-2e σ-coordination bonds between the remaining tangential Ni 3d orbitals (3dx2−y2 and 3dxy) and the η7-B7 heptagon around it. The IR, Raman, and UV-vis absorption spectra of 1–5 are computationally simulated to facilitate their experimental characterizations.

The recently observed cage-like borospherenes D

The experimentally observed planar hypercoordinate carbon species were detected in gas phase experiments and characterized by photoelectron spectroscopy. According to the Boltzmann distribution law, the thermodynamically favorable isomers, especially global minima, were relatively easier to detect than other isomers in such an experimental process. Here, we reported a thermodynamically unfavorable case, i.e., D3h CN3Mg3+ (1a), which we think is experimentally viable because all isomers that are energetically lower than 1a show bimolecular assembly type structures consisting of an N2 unit and various types of CNMg3+ units. The natural bond orbital (NBO) analysis suggests that the bonding between N2 and CNMg3+ is rather weak, and we think it is very hard to retain their basic structures when kinetic factors are considered. Consistently, the four lowest isomers in the second group show dissociation (to free N2 molecule and CNMg3+ cations) during Born–Oppenheimer molecular dynamic (BOMD) simulations. In contr...

Ethnopharmacological relevance Coptidis Rhizoma has been used to treat diabetes mellitus for more than 1400 years in China. Berberine, one of the main alkaloids of Coptidis Rhizoma, is a principal antidiabetic component of Coptidis Rhizoma. To investigate the effects of berberine on impaired neurogenic contractility of detrusor muscle from urinary bladder of rats with early stage diabetes. Materials and methods The detrusor muscle strips were isolated from urinary bladders of streptozotocin-induced diabetic rats, 5% sucrose-induced diuretic rats or normal rats, and were placed in organ bath. The contractions induced by electrical field stimulation (EFS), carbachol, KCl, adenosine triphosphate, and the effects of berberine on those contractions were measured. Results The EFS- or KCl-induced contraction of detrusor muscle was significantly decreased in diabetic rats as compared with diuretic or normal rats. Atropine and suramin inhibited EFS-induced contraction. In diabetic rats, the atropine sensitive components were decreased in EFS-induced contraction of detrusor muscle, and the adenosine triphosphate-induced contraction was significantly increased. The carbachol-induced contrations were not different among groups. Berberine significantly potentiated EFS-induced contractions of detrusor muscle both from normal and diabetic rats, but the potentiated effect of BBR was more sensitive to atropine in diabetic rats. Berberine also potentiated adenosine triphosphate-induced contraction of detrusor muscle, but did not change carbachol- or KCl-induced contraction. Conclusion The neurogenic contraction of urinary bladder detrusor muscle is decreased while purinergic contraction of bladder detrusor muscle is increased in rats with early stage diabetes. Berberine increases the neurogenic contractile response to EFS possibly via both presynaptic increasing neurotransmitters release and postsynaptic potentiation of purinergic transmitter-regulated response in rat urinary bladder detrusor; and in diabetic rats, berberine increases neurogenic contractile response mainly via the presynaptic increasing acetylcholine release.

The geometrical and electronic structures of a new class of transition-metal sandwich complexes M(C 6 X 6 Li 6 ) 2 (M = Cr, Mo, W; X = O, S) have been systematically investigated in this work at DFT B3LYP and PBE1PBE levels. Both the D 2d M(C 6 O 6 Li 6 ) 2 and D 6d M(C 6 S 6 Li 6 ) 2 (M = Cr, Mo, W) complex series are found to conform to the 18-electron rule similar to dibenzenechromium Cr(C 6 H 6 ) 2 and are stable in thermodynamics. Molecular orbital analyses indicate that effective d–π coordination bonds are formed between the partially filled n d atomic orbitals of transition-metal centers (Cr, Mo, W) and the π molecular orbitals of the C 6 X 6 Li 6 ligands (X = O, S). Electrostatic interactions between the two interlaced C 6 X 6 Li 6 (X = O and S) ligands also contribute to the high stability of these sandwich complexes. The calculated infrared spectra of these complexes are presented to facilitate their future experimental characterizations.

The most stable mono-layer boron sheets were predicted to have both the isolated hexagonal hole and the twin-hexagonal hole. Previous investigations indicate that planar B18H (n = 3–6, q = n − 4) are the building blocks of boron sheets with isolated hexagonal holes. Extensive DFT investigations performed in this work show that D 2h B26H8, D 2h B26H8 2+, and C 2 B26H6, may serve as the building blocks of boron sheets with twin-hexagonal holes. These bicyclic clusters possess planar or quasi-planar geometries at B3LYP/6-311+G(d,p) level, with 16, 14, and 14 delocalized π electrons, respectively. Detailed analyses indicate that they are overall aromatic in nature, with the formation of islands of both σ and π aromaticity. They are analogous to D 2h C16H14 and D 2h C16H14 2+ in π bonding patterns, respectively, but fundamentally different from the latter in σ-bonding. Remarkably, all of them appear to be energetically the lowest-lying isomers obtained, which are promising targets for future gas phase syntheses. These hydroboron clusters, together with B18H clusters, establish the molecular basis for modeling the short-range structures, nucleation, and growth processes of monolayer boron sheets. The results obtained in this work enrich the chemistry of boron hydride clusters and expand the analogy relationship between hydroborons and hydrocarbons.

Comprehensive first-principles calculations on the geometrical and electronic properties of C 5 O 5 - / 0 and C 6 O 6 - / 0 oxocarbons have been performed in this work. Both C 5 O 5 - monoanion and C5O5 neutral are found to possess perfect planar pentagonal structures at their ground states D5h C 5 O 5 - ( 2 A 2 ″ ) (1) and D5h C5O5 ( 1 A 2 ′ ) (2), while C 6 O 6 - and C6O6 appear to favor the slightly distorted quasi-planar C2v C 6 O 6 - (2A1) (3) and C2v C6O6 (1A1) (4), respectively. Adaptive natural density partitioning (AdNDP) analyses clearly reveal the σ- and π-bonding patterns of the monocyclic C n O n 2 - / - / 0 oxocarbons (n = 5 and 6). The adiabatic detachment energies (ADEs) and low-lying vertical detachment energies (VDEs) of the monoanions have been calculated at the coupled cluster level with triple excitations (CCSD(T)), with ADE = 3.723 and VDE = 3.776 eV for C 5 O 5 - and ADE = 3.629 eV and VDE = 3.679 eV for C 6 O 6 - CCSD(T)//MP2. The first excited states of the neutrals are predicted to have the approximate term values of T1 = 1.08 eV (3A2) for C5O5 and T1 = 1.22 eV (3B1) for C6O6. The predictions made in this work may help facilitate experimental characterizations of C 5 O 5 - and C 6 O 6 - monoanions.

We perform in this work a comprehensive first-principles investigation on the geometric and electronic structures of Au(BO) 2 − and Au(BS) 2 − which are valent isoelectronic to the well-known Au(CN) 2 − monoanion. Au(BO) 2 − and Au(BS) 2 − complexes prove to possess linear ground-state structures similar to Au(CN) 2 − and the BO− and BS− ligands in them are found to be coordinated terminally via boron atoms to gold centers which are weakly negatively charged. Au–B bonds in Au(BO) 2 − and Au(BS) 2 − appear to have higher Wiberg bond indices (0.79 and 0.80) and more covalent components (60 and 53 %) than the corresponding values of Au–C interaction in Au(CN) 2 − (0.67 and 39 %, respectively) at the same theoretical levels. Their Au–B bifurcation values of the electronic localization function also turn out to be higher than Au–C. These results strongly suggest that the Au–B bonds in Au(BO) 2 − and Au(BS) 2 − with multiple-bond character possess stronger covalent characters than Au–C in Au(CN) 2 − .

Motifs of planar metalloborophenes, cage-like metalloborospherenes, and metal-centered double-ring tubular boron species have been reported. Based on extensive first-principles theory calculations, we present herein the possibility of doping the quasi-planar C2v B56 (A-1) with an alkaline-earth metal to produce the penta-ring tubular Ca©B56 (B-1) which is the most stable isomer of the system obtained and can be viewed as the embryo of metal-doped (4,0) boron α-nanotube Ca©BNT(4,0) (C-1). Ca©BNT(4,0) (C-1) can be constructed by rolling up the most stable boron α-sheet and is predicted to be metallic in nature. Detailed bonding analyses show that the highly stable planar C2v B56 (A-1) is the boron analog of circumbiphenyl (C38H16) in π-bonding, while the 3D aromatic C4v Ca©B56 (B-1) possesses a perfect delocalized π system over the σ-skeleton on the tube surface. The IR and Raman spectra of C4v Ca©B56 (B-1) and photoelectron spectrum of its monoanion C4v Ca©B56− are computationally simulated to facilitate their spectroscopic characterizations.

The recent discovery of perfect cage-like D 2d B40 − and D 2d B40 (all-boron fullerenes) has led to the emergence of a borospherene family. However, the geometrical and electronic structures of their cationic counterpart B40 +, previously detected in gas phase, remain unknown to date. Based on extensive first-principles theory calculations, we present herein the possibility of a perfect cage-like D 2d B40 + (1) (2A1) for the monocation, which turns out to be the global minimum of the system similar to B40 − and B40, adding a new member to the borospherene family. Molecular dynamics simulations indicate that D 2d B40 + (1) is dynamically stable at 300 K, whereas it starts to fluctuate at 500 K between the two lowest-lying isomers D 2d B40 + (1) (W) and C s B40 + (3) (M) in concerted W-X-M mechanisms via the transition state of C 1 B40 + (X), with forward (W → X → M) and backward (M → X → W) activation energies (Ea) of 14.6 and 6.9 kcal mol−1, respectively. The spectra from IR, Raman, and UV–vis analyses were simulated to facilitate future characterization of this important borospherene monocation.