Triosephosphate isomerase 1 may be a risk predictor in laryngeal squamous cell carcinoma: a multi-centered study integrating bulk RNA, single-cell RNA, and protein immunohistochemistry.

BACKGROUND: Although great progress has been made in anti-cancer therapy, the prognosis of laryngeal squamous cell carcinoma (LSCC) patients remains unsatisfied. Quantities of studies demonstrate that glycolytic reprograming is essential for the progression of cancers, where triosephosphate isomerase 1 (TPI1) serves as a catalytic enzyme. However, the clinicopathological significance and potential biological functions of TPI1 underlying LSCC remains obscure. METHODS: We collected in-house 82 LSCC tissue specimens and 56 non-tumor tissue specimens. Tissue microarrays (TMA) and immunohistochemical (IHC) experiments were performed. External LSCC microarrays and bulk RNA sequencing data were integrated to evaluate the expression of TPI1. We used a log-rank test and the CIBERSORT algorithm to assess the prognostic value of TPI1 and its association with the LSCC microenvironment. Malignant laryngeal epithelial cells and immune-stromal cells were identified using inferCNV and CellTypist. We conducted a comprehensive analysis to elucidate the molecular functions of TPI1 in LSCC tissue and single cells using Pearson correlation analysis, high dimensional weighted gene co-expression analysis, gene set enrichment analysis, and clustered regularly interspaced short palindromic repeats (CRISPR) screen. We explored intercellular communication patterns between LSCC single cells and immune-stromal cells and predicted several therapeutic agents targeting TPI1. RESULTS: Based on the in-house TMA and IHC analysis, TPI1 protein was found to have a strong positive expression in the nucleus of LSCC cells but only weakly positive activity in the cytoplasm of normal laryngeal cells (p < 0.0001). Further confirmation of elevated TPI1 mRNA expression was obtained from external datasets, comparing 251 LSCC tissue samples to 136 non-LSCC tissue samples (standardized mean difference = 1.06). The upregulated TPI1 mRNA demonstrated a high discriminative ability between LSCC and non-LSCC tissue (area under the curve = 0.91; sensitivity = 0.87; specificity = 0.79), suggesting its potential as a predictive marker for poor prognosis (p = 0.037). Lower infiltration abundance was found for plasma cells, naïve B cells, monocytes, and neutrophils in TPI-high expression LSCC tissue. Glycolysis and cell cycle were significantly enriched pathways for both LSCC tissue and single cells, where heat shock protein family B member 1, TPI1, and enolase 1 occupied a central position. Four outgoing communication patterns and two incoming communication patterns were identified from the intercellular communication networks. TPI1 was predicted as an oncogene in LSCC, with CRISPR scores less than -1 across 71.43% of the LSCC cell lines. TPI1 was positively correlated with the half maximal inhibitory concentration of gemcitabine and cladribine. CONCLUSIONS: TPI1 is dramatically overexpressed in LSCC than in normal tissue, and the high expression of TPI1 may promote LSCC deterioration through its metabolic and non-metabolic functions. This study contributes to advancing our knowledge of LSCC pathogenesis and may have implications for the development of targeted therapies in the future.

Structural Evolution and Electronic Properties of V2Sin-/0 (n = 7-14) Clusters: Anion Photoelectron Spectroscopy and Theoretical Calculations.

A systematic study of the structures and electronic properties of V2-doped silicon clusters, V2Sin-/0 (n = 7-14), was carried out by anion photoelectron spectroscopic experiments combined with theoretical calculations. According to the experimental spectra of V2Sin- (n = 7-14) clusters, the V2Si12- cluster has the highest vertical detachment energy (VDE) of 3.66 eV, while V2Si7- and V2Si14- clusters have lower VDEs of 2.81 and 2.84 eV, respectively. The most stable structure searches find that two V atoms in the V2Sin- clusters with size n = 7 and 8 are located at the surface, while V2Sin- clusters with n ≥ 9 prefer cage-like structures. Based on the analysis of the structural evolution of V2Sin- (n = 9-14) clusters, it can be clearly seen how the antihexagonal prism with one V encapsulated in the cage is gradually built from n = 9 to 12 and further developed from n = 12 to 14 with the extra silicon atoms located at the surface of the Si12 cage. The molecular orbital and the atoms in molecule analysis of the V2Sin- (n = 7-14) anions demonstrate that the strong V-V bond and the delocalized interaction between the V2 moiety and the Sin ligand play a significant role in stabilizing the cluster structures. A strong linear correlation has been found between the Wiberg bond order of the V-V bond and the electron density at the V-V bond critical points.

Clinicopathological value of hematopoietic cell kinase overexpression in laryngeal squamous cell carcinoma tissues.

Laryngeal squamous cell carcinoma (LSCC) is the most lethal cancer in head and neck tumors. Although hematopoietic cell kinase (HCK) has been proven to be an oncogene in several solid tumors, its roles in LSCC remain obscure. This is the first study to evaluate the clinical value of HCK in LSCC, with the aim of exploring its expression status and potential molecular mechanisms underlying LSCC. LSCC tissue-derived gene chips and RNA-seq data were collected for a quantitive integration of HCK mRNA expression level. To confirm the protein expression level of HCK, a total of 82 LSCC tissue specimens and 56 non-tumor laryngeal epithelial controls were collected for in-house tissue microarrays and immunohistochemical staining. Kaplan-Meier curves were generated to determine the ability of HCK in predicting overall survival, progress-free survival, and disease-free survival of LSCC patients. LSCC overexpressed genes and HCK co-expressed genes were intersected to preliminarily explore the enriched signaling pathways of HCK. It was noticed that HCK mRNA was markedly overexpressed in 323 LSCC tissues compared with 196 non-LSCC controls (standardized mean difference = 0.81, p < 0.0001). Upregulated HCK mRNA displayed a moderate discriminatory ability between LSCC tissues and non-tumor laryngeal epithelial controls (area under the curve = 0.78, sensitivity = 0.76, specificity = 0.68). The higher expression level of HCK mRNA could predict worse overall survival and disease-free survival for LSCC patients (p = 0.041 and p = 0.013). Lastly, upregulated co-expression genes of HCK were significantly enriched in leukocyte cell-cell adhesion, secretory granule membrane, and extracellular matrix structural constituent. Immune-related pathways were the predominantly activated signals, such as cytokine-cytokine receptor interaction, Th17 cell differentiation, and Toll-like receptor signaling pathway. In conclusion, HCK was upregulated in LSCC tissues and could be utilized as a risk predictor. HCK may promote the development of LSCC by disturbing immune signaling pathways.

Theoretical study on exohedral complexes C6H6TMB40 (TM = Sc-Ni).

Exohedral borospherene complexes comprised of 3d transition metal (TM) atoms with borospherene B40 and benzene (C6H6) molecules, C6H6TMB40, were systematically studied by using density functional theory (DFT). Results show that in the ground states, the bonding type between TM and B40 changes from η7 (TM = Sc-V) to η6 (TM = Cr-Fe) and then to η7 (TM = Co, Ni) with the increasing number of d electrons. Except for C6H6TiB40 and C6H6FeB40 being triplets, all C6H6TMB40 clusters have the lowest spin. Namely, the ground spin state with an even number of electrons is a singlet state, and the ground spin state with an odd number of electrons is a doublet state. The investigated C6H6TMB40 clusters (TM = Sc-Ni) possess higher stabilities through the ionic-covalent interactions between transition metals, benzene and the B40 cage.

Quanzhenyiqitang Reverses LPS-Induced Inflammation via Inhibiting PYK2/p38MAPK/HDAC2/CK2 Signaling Pathway in Rat Alveolar Macrophage.

Chronic obstructive pulmonary disease (COPD) is a common chronic pulmonary disease with multiple etiologies and pathological changes. PYK2 expression is significantly increased in lipopolysaccharide-induced lung injury, but it mediates chronic lung inflammation. The mechanism of its occurrence remains unclear. Quanzhenyiqitang is often used in clinical treatment of COPD, so this study explored the mechanism of its treatment of lipopolysaccharide-induced lung injury. In this study, transfection, flow cytometry, QRT-PCR, and Western blotting methods were used to study the mechanism of Quanzhenyiqitang lipopolysaccharide-induced lung injury. The results showed that the mechanism of occurrence remains unclear. Our novel observations imply that the PYK2/p38MAPK/HDAC2/CK2 pathway is one of the fundamental underlying mechanisms that mediate the pathogenic progression of COPD, and Quanzhenyiqitang may be the therapeutic drug to prevent chronic inflammation and delay the progression of COPD by inhibiting PYK2 signaling pathways.

SNHG16 promotes hepatocellular carcinoma development via activating ECM receptor interaction pathway.

BACKGROUND: Accumulating data have suggested that long non-coding RNAs (lncRNAs) play important roles in regulating tumor cell growth. This study was designed to investigate the role of SNHG16 in hepatocellular carcinoma (HCC). METHODS: SNHG16 expression was detected with real-time polymerase chain reaction (PCR). The cutoff value of SNHG16 for tumor-free survival (TFS) was determined with receiver operating characteristic curve analysis. Small interfering RNA was used to inhibit the expression of SNHG16 in HCC cell lines. The biologic behavior of HCC cell was determined with cell viability assay and Transwell assay in vitro. The potential predictive value of SNHG16 on prognosis was analyzed by Kaplan-Meier curves and Cox proportional hazards regression model. RESULTS: SNHG16 expression was upregulated in tumor tissues and HCC cell lines. High expression of SNHG16 was associated with tumor recurrence and poor prognosis after surgery. Multivariate analysis revealed that SNHG16 was an independent prognostic factor for poor recurrence-free survival. Moreover, inhibition of SNHG16 in HepG2, Hep3B, and BEL-7402 cells significantly reduced cell invasiveness and proliferation. Mechanistic analyses indicated that the ECM-receptor interaction pathway was remarkably activated by SNHG16. CONCLUSIONS: SNHG16 might be a promising biomarker for predicting tumor recurrence in HCC patients after surgery and a potential therapeutic target for HCC.

On the nature of bonding in a new boronyl species Zn2(BO)2: a linear four-center two-electron σ bond.

The Zn-Zn bond as one of the metal-to-metal bonds in clusters and molecules is of fundamental interest in many areas of natural science. Neutral boronyl can be viewed as a σ radical and is found in boronyl metal complexes. However, a complex with the Zn-Zn bond stabilized by boronyl ligands has not been found so far. Herein, we report on the computational design of the simplest case of such a system: linear D∞h OBZnZnBO. The structural and electronic properties and chemical bonding on a series of zinc complexes Znx(BO)y (x = 1,2; y = 1,2) with boronyl as ligands have been studied using quantum chemical calculations at the B3LYP and PBE0 levels, respectively. For the Zn2(BO)2 cluster, the linear D∞h OBZnZnBO is the global minimum, in which the calculated Zn-Zn bond length of rZn-Zn = 2.400 Å at the B3LYP level, which appears to be close to the latest recommended covalent radii (2.40 Å) of the proposed single bond covalent radii of the Zn-Zn bond. Chemical bonding analyses show that D∞h OBZnZnBO possesses a linear four-center two-electron (4c-2e) σ bond. The σ bond framework has a contribution of Zn orbitals 54% and B orbitals 44%, which involve Zn 4s 20% and 4p 34%, and B 2s 28% and 2p 16%, respectively. Furthermore, the D∞h HZnZnH and NCZnZnCN clusters also exhibit one linear 4c-2e σ bond due to the secondary contribution from the H s and C sp components, respectively. The linear 4c-2e σ bond greatly stabilizes the dizinc complexes. D∞h OBZnZnBO is thermochemically stable with respect to the possible formation channel at room temperature, whereas the formation energy of the exergonic channel, 2ZnBO (C∞v, 2Σg) → OBZnZnBO (D∞h, 1Σg), is evaluated to be -58.75 kcal mol-1 at the B3LYP level. Thus, D∞h OBZnZnBO as the first observation of the Zn-Zn covalent bond in zinc complexes with boronyl as ligands may be synthesized in laboratories in the near future.

Appearance of V-encapsulated tetragonal prism motifs in VSi10- and VSi11- clusters.

The structural and electronic properties of V-doped silicon clusters, VSi10-/0 and VSi11-/0, were investigated by using mass-selected anion photoelectron spectroscopy in combination with theoretical calculations. Photoelectron spectroscopy of VSi10- and VSi11- clusters with spectral similarity reveals that the two cluster structures resemble each other. Interestingly, theoretical calculation studies provide definitive evidence of the global minima for the two clusters to be V-encapsulated tetragonal prism motifs with extra Si atoms bicapped and tricapped, respectively. The enhanced stability of the tetragonal prism unit in VSi10- and VSi11- is due to the strong interactions between 3d (V) and 3p (Si) orbitals, and more charge transfers from the Sin framework to the encapsulated V atom. The tetragonal prism unit possessed by both the VSi10- and VSi11- clusters is observed for the first time in the current work, and may offer new ideas in developing components for Si-based nanodevices.

Theoretical insights into the hydrogen bonding interaction in the complexation of epinephrine with uracil.

The present study is aimed at probing the hydrogen bonding interaction between epinephrine and uracil by means of density functional theory calculations concerning their complexation's geometries, interaction energies, and vibrational frequencies. Geometry optimization was carried out giving 19 stable geometries of epinephrine-uracil complex with interaction energies in a range of - 21.51 to - 62.37 kJ mol-1 using the basis set superposition error (BSSE) correction. The analysis of structure and vibration shows that the hydrogen bonding elongates the length of corresponding bond O(N)-H and decreases the symmetric stretching vibrational frequency, which indicates red-shifted H-bonding interactions in all the geometries. Additionally, the analysis with theories of natural bond orbital (NBO), atoms in molecules (AIM), and the reduced density gradient (RDG) of hydrogen bonding properties and characteristics of the 19 geometries suggests that the hydrogen bonding in all the optimized structures of epinephrine-uracil complex is kind of a closed-shell interaction and mainly electrostatic dominant.

Effect of poly-arginine R18 on neurocyte cell growth via autophagy in traumatic brain injury.

The present study assessed the effects of poly-arginine R18 and its promotion of neurocyte cell growth via autophagy in traumatic brain injury (TBI), and aimed to determine the possible mechanism by which this occurs. Brain water content was measured to analyze the effects of poly-arginine R18 in TBI. MTT and lactate dehydrogenase activity assays were performed to measure N2A cell growth. Western blotting and immunofluorescence staining were also performed to determine the protein expression of Bcl-2 associated X, LC3, Beclin-1 and p62. The results demonstrated that poly-arginine R18 treatment reduced neurocyte apoptosis and promoted neurocyte cell growth via the activation of autophagy in a rat model of TBI. Furthermore, poly-arginine R18 treatment promoted neurocyte cell growth, reduced apoptosis, induced the protein expression of LC3 and Beclin-1, and suppressed p62 expression by promoting autophagy in vitro. In addition, the inhibition of autophagy attenuated the effects of poly-arginine R18 on cell growth in vitro. Collectively, the results demonstrate the effects of poly-arginine R18 on neurocyte cell growth via autophagy activation in a model of TBI, and poly-arginine R18 is therefore a potential therapeutic target in TBI.

Planar Tricyclic B8O8 and B8O8- Clusters: Boron Oxide Analogues of s-Indacene C12H8.

Boron clusters and their oxides are electron-deficient species with (π and σ) aromaticity and antiaromaticity, enabling a structural and bonding analogy between them and the aromatic hydrocarbons. s-Indacene C12H8 is normally considered as a border system between the classes of aromatic and antiaromatic hydrocarbons. We show herein, via computer global-minimum searches and B3LYP and single-point CCSD(T) calculations, that boron oxide clusters D2h B8O8 (1, 1Ag) and D2h B8O8- (2, 2B2g) adopt planar tricyclic structures, which feature fused heterocyclic B3O2/B4O2/B3O2 rings and two boronyl (BO) terminals, a structural pattern analogous to the C5/C6/C5 rings in s-indacene. Bonding analyses indicate that B8O8 (1) is a formally antiaromatic 12π system, the molecular orbitals of which are largely similar to those of s-indacene. Infrared and ultraviolet-visible spectra of B8O8 (1) neutral, as well as the photoelectron spectrum of B8O8- (2) anion, are predicted computationally. The latter spectrum shows a sizable energy gap of 3.5 eV for 2, demonstrating the electronic robustness of 1. Our bonding analyses also shed critical light on the nature of bonding in s-indacene.

Pentagonal five-center four-electron π bond in ternary B3N2H5 cluster: an extension of the concept of three-center four-electron ω bond.

Boron-based heteroatomic rings can have exotic chemical bonding, in which the p lone-pairs of heteroatoms manage to participate in delocalized π bonding, compensating for boron's electron-deficiency. We explore herein the bonding properties of ternary B-N-H systems with a pentagonal ring, using the B3N2H50/-/2- clusters as examples. Computational structural searches lead to perfectly planar C2v B3N2H5 (1, 1A1) and C2v B3N2H5- (2, 2B1) as global minima for the neutral species and monoanion, which feature a pentagonal B3N2 ring. The corresponding dianion C2v B3N2H52- (3, 1A1) is a local minimum, whose global minimum adopts a chain-like open structure. Bonding analyses reveal a five-center four-electron (5c-4e) π system in 1, dubbed the 5c-4e o-bond. It is a 4π system in the bonding/nonbonding combination, originating from two N 2p lone-pairs, which can be considered as an extension of the concept of 3c-4e ω-bond. The extra electrons in 2 and 3 occupy a markedly destabilized π orbital. Thus, a 4π configuration, rather than a π sextet according to the (4n + 2) Hückel rule, is electronically robust for the B3N2H50/-/2- system. Infrared and photoelectron spectra are predicted for 1 and 2, respectively. Structural evolution of ring-like and chain-like isomers with charge-state in B3N2H50/-/2- is elucidated. B3N2H5- (2) is used as ligand for sandwich-type complexes: C2h [(B3N2H5)2Fe]2- and C2h [(B3N2H5)2Fe]Li2.

Concentric dual π aromaticity in bowl-like B30 cluster: an all-boron analogue of corannulene.

A chemical bonding model is presented for the bowl-like C5v B30 global-minimum cluster with a central pentagonal hole. The B30 cluster is composed of three concentric boron rings: first B5, second B10, and third B15. The first and second B rings constitute an inner double-chain ribbon and support a delocalized π sextet. The second and third rings form an outer double-chain ribbon, where 14π delocalized electrons are situated. The unique π systems lead to concentric dual π aromaticity for B30, a concept established from concerted computational data on the bases of canonical molecular orbital (CMO) analysis, adaptive natural density partitioning (AdNDP), nucleus-independent chemical shifts (NICS), and natural charge calculations. A proposal is put forward that the bowl-like B30 cluster is an exact all-boron analogue of corannulene (C20H10), a fragment of C60 fullerene. The bonding nature of corannulene is revisited and fully elucidated herein. A comparison of the bonding patterns in bowl-like C5v B30 cluster and two other structural isomers (Cs and C1) unravels the mechanism as to why the defective hole prefers to be positioned at the center.

[Sb4Au4Sb4](2-): A designer all-metal aromatic sandwich.

We report on the computational design of an all-metal aromatic sandwich, [Sb4Au4Sb4](2-). The triple-layered, square-prismatic sandwich complex is the global minimum of the system from Coalescence Kick and Minima Hopping structural searches. Following a standard, qualitative chemical bonding analysis via canonical molecular orbitals, the sandwich complex can be formally described as [Sb4](+)[Au4](4-)[Sb4](+), showing ionic bonding characters with electron transfers in between the Sb4/Au4/Sb4 layers. For an in-depth understanding of the system, one needs to go beyond the above picture. Significant Sb → Au donation and Sb ← Au back-donation occur, redistributing electrons from the Sb4/Au4/Sb4 layers to the interlayer Sb-Au-Sb edges, which effectively lead to four Sb-Au-Sb three-center two-electron bonds. The complex is a system with 30 valence electrons, excluding the Sb 5s and Au 5d lone-pairs. The two [Sb4](+) ligands constitute an unusual three-fold (π and σ) aromatic system with all 22 electrons being delocalized. An energy gap of ∼1.6 eV is predicted for this all-metal sandwich. The complex is a rare example for rational design of cluster compounds and invites forth-coming synthetic efforts.

Planar B3S2H3(-) and B3S2H3 clusters with a five-membered B3S2 ring: boron-sulfur hydride analogues of cyclopentadiene.

Boron clusters can serve as inorganic analogues of hydrocarbons or polycyclic aromatic hydrocarbons (PAHs). We present herein, based upon global searches and electronic structural calculations at the B3LYP and CCSD(T) levels, the global-minimum structures of two boron-sulfur hydride clusters: C2v B3S2H3(-) (1, (2)B1) and C2v B3S2H3 (2, (1)A1). Both species are perfectly planar and feature a five-membered B3S2 ring as the structural core, with three H atoms attached terminally to the B sites. Chemical bonding analysis shows that C2v B3S2H3(-) (1) has a delocalized 5π system within a heteroatomic B3S2 ring, analogous to the π bonding in cyclopentadiene, D5h C5H5. The corresponding closed-shell C2v B3S2H3(2-) (3, (1)A1) dianion is only a local minimum. At the single-point CCSD(T) level, it is 5.7 kcal mol(-1) above the chain-like C1 ((1)A) open structure. This situation is in contrast to the cyclopentadienyl anion, C5H5(-), a prototypical aromatic hydrocarbon with a π sextet. The C2v B3S2H3 (2) neutral cluster is readily obtained upon removal of one π electron from C2v B3S2H3(-) (1). The anion photoelectron spectrum of C2v B3S2H3(-) (1) and the infrared absorption spectrum of C2v B3S2H3 (2) are predicted. The C2v B3S2H3(-) (1) species can be stabilized in sandwich-type C2h [(B3S2H3)2Fe](2-) and salt C2h [(B3S2H3)2Fe]Li2 complexes. An intriguing difference is observed between the pattern of π sextet in C2v B3S2H3(2-) (3) dianion and that in cyclopentadienyl anion. The present work also sheds light on the mechanism of structural evolution in the B3S2H3(0/-/2-) series with charge states.

On the nature of chemical bonding in the all-metal aromatic [Sb3Au3Sb3](3-) sandwich complex.

In a recent communication, an all-metal aromatic sandwich [Sb3Au3Sb3](3-) was synthesized and characterized. We report herein a density-functional theory (DFT) study on the chemical bonding of this unique cluster, which makes use of a number of computational tools, including the canonical molecular orbital (CMO), adaptive natural density partitioning (AdNDP), Wiberg bond index, and orbital composition analyses. The 24-electron, triangular prismatic sandwich is intrinsically electron-deficient, being held together via six Sb-Sb, three Au-Au, and six Sb-Au links. A standard, qualitative bonding analysis suggests that all CMOs are primarily located on the three Sb3/Au3/Sb3 layers, three Au 6s based CMOs are fully occupied, and the three extra charges are equally shared by the two cyclo-Sb3 ligands. This bonding picture is referred to as the zeroth order model, in which the cluster can be formally formulated as [Sb3(1.5+)Au3(3-)Sb3(1.5+)](3-) or [Sb3(0)Au3(3-)Sb3(0)]. However, the system is far more complex and covalent than the above picture. Seventeen CMOs out of 33 in total involve remarkable Sb → Au electron donation and Sb ← Au back-donation, which are characteristic of covalent bonding and effectively redistribute electrons from the Sb3 and Au3 layers to the interlayer edges. This effect collectively leads to three Sb-Au-Sb three-center two-electron (3c-2e) σ bonds as revealed in the AdNDP analyses, despite the fact that not a single such bond can be identified from the CMOs. Orbital composition analyses for the 17 CMOs allow a quantitative understanding of how electron donation and back-donation redistribute the charges within the system from the formal Sb3(0)/Au3(3-) charge states in the zeroth order model to the effective Sb3(1.5-)/Au3(0) charge states, the latter being revealed from the natural bond orbital analysis.

On the nature of bonding in binary Be2O2 and Si2O2 clusters: rhombic four-center four-electron π and σ bonds.

The structural and electronic properties and chemical bonding of binary Be2O2 and Si2O2 clusters have been studied using quantum chemical calculations at the B3LYP level. For the Be2O2 cluster, the potential energy surface is probed by unbiased structural searches and the global-minimum structure was established using the B3LYP calculations, complemented by PBE0 and single-point CCSD(T) calculations for top isomers. The perfectly planar D2h Be2O2 ((1)Ag) global minimum is well defined, being at least 3.64 eV lower in energy than alternative structures at the CCSD(T)//B3LYP/aug-cc-pVTZ level. Chemical bonding analyses show that D2h Be2O2 and Si2O2 clusters possess the rhombic four-center four-electron (4c-4e) π bond, that is, the o-bond, a conception derived from electron-deficient boron oxide clusters lately. Furthermore, the Be2O2 and Si2O2 clusters also exhibit rhombic 4c-4e σ bonds, both for the radial and tangential σ frameworks (σr and σt). The σt framework is classified as an o-bond only formally, due to the secondary contribution from the Be/Si s component. The three-fold (π, σr, and σt) o-bonds in Be2O2 and Si2O2 are considered to resemble the three-fold aromaticity in all-metal Al4(2-) dianions. A 4c-4e o-bond makes use of four O 2p electrons, which would otherwise be two lone-pairs, for a delocalized and completely bonding orbital, as well as a residual nonbonding orbital. Three-fold o-bonds thus greatly stabilize the binary Be2O2 and Si2O2 clusters. We anticipate that the bonding concept should be applicable to additional molecular systems, including those with larger heterocyclic rings.

A first-principles study on the B5O5 (+/0) and B5O5 (-) clusters: The boron oxide analogs of C6H5 (+/0) and CH3Cl.

The concept of boronyl (BO) and the BO/H isolobal analogy build an interesting structural link between boron oxide clusters and hydrocarbons. Based upon global-minimum searches and first-principles electronic structural calculations, we present here the perfectly planar C2v B5O5 (+) (1, (1)A1), C2v B5O5 (2, (2)A1), and tetrahedral Cs B5O5 (-) (3, (1)A') clusters, which are the global minima of the systems. Structural and molecular orbital analyses indicate that C2v B5O5 (+) (1) [B3O3(BO)2 (+)] and C2v B5O5 (2) [B3O3(BO)2] feature an aromatic six-membered boroxol (B3O3) ring as the core with two equivalent boronyl terminals, similar to the recently reported boronyl boroxine D3h B6O6 [B3O3(BO)3]; whereas Cs B5O5 (-) (3) [B(BO)3(OBO)(-)] is characterized with a tetrahedral B(-) center, terminated with three BO groups and one OBO unit, similar to the previously predicted boronyl methane Td B5O4 (-) [B(BO)4 (-)]. Alternatively, the 1-3 clusters can be viewed as the boron oxide analogs of phenyl cation C6H5 (+), phenyl radical C6H5, and chloromethane CH3Cl, respectively. Chemical bonding analyses also reveal a dual three-center four-electron (3c-4e) π hyperbond in Cs B5O5 (-) (3). The infrared absorption spectra of B5O5 (+) (1), B5O5 (2), and B5O5 (-) (3) and anion photoelectron spectrum of B5O5 (-) (3) are predicted to facilitate their forthcoming experimental characterizations. The present work completes the BnOn (+/0/-) series for n = 1-6 and enriches the analogous relationship between boron oxides and hydrocarbons.

Crystal structure of 1-ethyl-5-iodo-indolin-2-one.

In the title indolinone derivative, C10H10INO, all the non-H atoms, except the terminal methyl C atom, are almost coplanar. The mol-ecules are arranged into columns extending along the a-axis direction and inter-act with the mol-ecules in adjacent columns via C-H⋯O hydrogen bonds [H⋯O distance = 2.57 (3) Å] and I⋯I short contacts of 3.8986 (3) Å. A one-dimensional zigzag iodine chain along the a axis is apparent between two neighbouring columns.