QRFP and GPR103 in the paraventricular nucleus play a role in chronic stress-induced depressive-like symptomatology by enhancing the hypothalamic-pituitary-adrenal axis.

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis during chronic stress is essential for depression neurobiology. As the latest member of the RFamide peptide family in mammals, pyroglutamylated RFamide peptide (QRFP) is closely implicated in neuroendocrine maintenance by activating G-protein-coupled receptor 103 (GPR103). We hypothesized that QRFP and GPR103 might contribute to chronic stress-induced depression by promoting corticotropin-releasing hormone (CRH) release from neurons in the paraventricular nucleus (PVN), and various methods were employed in this study, with male C57BL/6J mice adopted as the experimental subjects. Chronic stress induced not only depression-like behaviors but also significant enhancement in QRFP and GPR103 in the PVN. Genetic overexpression of QRFP/GPR103 and stereotactic infusion of QRFP-26/QRFP-43 peptide in the PVN all mimicked chronic stress that induced various depression-like phenotypes in naïve mice, and this was mediated by promoting CRH biosynthesis and HPA activity. In contrast, genetic knockdown of QRFP/GPR103 in the PVN produced notable antidepressant-like effects in mice exposed to chronic stress. Furthermore, genetic knockout of QRFP also protected against chronic stress in mice. In addition, both the C-terminal biological region of QRFP and the downstream PKA/PKC-CREB signaling coupled to GPR103 stimulation underlie the role of QRFP and GPR103 in depression. Collectively, QRFP and GPR103 in PVN neurons could be viable targets for novel antidepressants.

Probing the Structures and Lanthanum-Lanthanum Bonding in La2Bn- (n = 4-6) Clusters.

We report an investigation on the structures and chemical bonding in a series of di-lanthanum boron clusters, La2Bn- (n = 4-6), using photoelectron spectroscopy and theoretical calculations. Well-resolved photoelectron spectra are obtained and used to verify the global minima of the lanthanide boron clusters. The structures of La2B4- and La2B5- are found to consist of open B4 and B5 rings, respectively, around the La2 dimer equatorially. Theoretical evidence of La-La σ bonding is obtained in La2B4-, whereas the bonding in La2B5- is similar to that of an incomplete inverse sandwich without real La-La bonding. The global minimum of La2B6- is completely different, where one of the La atoms can be viewed as substituting a B atom of the B7 cluster due to the high electronic stability of the B73- borozene. The resulting lanthaborozene [LaB6]3- forms a half-sandwich structure with the second La atom, with evidence of La-La σ bonding. Lanthanide-lanthanide bonds are relatively rare in chemistry. The current work suggests that binary lanthanide boron clusters provide interesting systems to study lanthanide-lanthanide bonding.

MiR-184-3p in the paraventricular nucleus participates in the neurobiology of depression via regulation of the hypothalamus-pituitary-adrenal axis.

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis during chronic stress is essential for the pathogenesis of depression, and increased activity of cAMP response element binding protein (CREB)-regulated transcription co-activator 1 (CRTC1) in the paraventricular nucleus (PVN) plays a critical role. As a well-investigated microRNA (miRNA), miR-184 has two forms, miR-184-3p and miR-184-5p. Recently, miRNAs target genes predictive analysis and dual-luciferase reporter assays identified an inhibitory role of miR-184-3p on CRTC1 expression. Therefore, we speculated that miR-184-3p regulation was responsible for the effects of chronic stress on CRTC1 in the PVN. Various methods, including the chronic social defeat stress (CSDS) model of depression, behavioral tests, Western blotting, co-immunoprecipitation (Co-IP), quantitative real-time reverse transcription PCR (qRT-PCR), immunofluorescence, and adeno-associated virus (AAV)-mediated gene transfer, were used. CSDS evidently downregulated the level of miR-184-3p, but not miR-184-5p, in the PVN. Genetic knockdown and pharmacological inhibition of miR-184-3p in the PVN induced various depressive-like symptoms (e.g., abnormal behaviors, HPA hyperactivity, enhanced CRTC1 function in PVN neurons, downregulation of hippocampal neurogenesis, and decreased brain-derived neurotrophic factor (BDNF) signaling) in naïve male C57BL/6J mice. In contrast, genetic overexpression and pharmacological activation of miR-184-3p in the PVN produced significant beneficial effects against CSDS. MiR-184-3p in the PVN was necessary for the antidepressant actions of two well-known SSRIs, fluoxetine and paroxetine. Collectively. miR-184-3p was also implicated in the neurobiology of depression and may be a viable target for novel antidepressants.

Hippocampal SorCS2 overexpression represses chronic stress-induced depressive-like behaviors by promoting the BDNF-TrkB system.

BACKGROUND: Emerging data has demonstrated that in mature neurons, SorCS2 localizes to the postsynaptic density of dendritic spines and facilitates plasma membrane sorting of TrkB by interacting with it, transmitting positive signaling from BDNF on neurons. Thus, it is possible that SorCS2 plays a role in the pathophysiology of depression by regulating the BDNF-TrkB system. METHODS: In the present study, SorCS2 expression in different brain regions [hippocampus, medial prefrontal cortex (mPFC), hypothalamus, amygdala, ventral tegmental area (VTA), and nucleus accumbens (NAc)] was thoroughly investigated in the chronic social defeat stress (CSDS) and chronic unpredictable mild stress (CUMS) models of depression. The changes in depressive-like behaviors, the hippocampal BDNF signaling cascade, and amounts of hippocampal immature neurons were further investigated after SorCS2 overexpression by microinjection of the adenovirus associated virus vector containing the coding sequence of mouse SorCS2 (AAV-SorCS2) into the hippocampus of mice exposed to CSDS or CUMS. RESULTS: It was found that both CSDS and CUMS significantly decreased the protein and mRNA expression of SorCS2 in the hippocampus but not in other brain regions. Chronic stress also notably downregulated the level of hippocampal SorCS2-TrkB binding in mice. In contrast, AAV-based genetic overexpression of hippocampal SorCS2 fully reversed the chronic stress-induced not only depressive-like behaviors but also decreased SorCS2-TrkB binding, BDNF signaling pathway, and amounts of immature neurons in the hippocampus of mice. CONCLUSION: All these results suggest that enhancing the hippocampal SorCS2 expression protects against chronic stress, producing antidepressant-like actions. Hippocampal SorCS2 may participate in depression neurobiology and be a potential antidepressant target. SIGNIFICANCE STATEMENT: Targeting of proteins to distinct subcellular compartments is essential for neuronal activity and modulated by VPS10P domain receptors which include SorCS2. In mature neurons, SorCS2 localizes to the postsynaptic density of dendritic spines and facilitates plasma membrane sorting of TrkB by interacting with it, transmitting positive signaling from BDNF on neurons. Our study is the first direct evidence preliminarily showing that SorCS2 plays a role in depression neurobiology. It was found that chronic stress induced not only depressive-like behaviors but also decreased SorCS2 expression in the hippocampus. Chronic stress did not affect SorCS2 expression in the mPFC, hypothalamus, amygdala, VTA, or NAc. In contrast, genetic overexpression of hippocampal SorCS2 prevented against chronic stress, producing antidepressant-like actions in mice. Thus, hippocampal SorCS2 is a potential participant underlying depression neurobiology and may be a novel antidepressant target. Our study may also extend the knowledge of the neurotrophic hypothesis of depression.

Deep Eutectic Solvent-Assisted Corrosion Boosting Bulk FeCoNiCrMo High-Entropy Alloys as Highly Efficient Oxygen Evolution Reaction Catalyst.

The key to enhancing water electrolysis efficiency lies in selecting highly efficient catalysts. Currently, high-entropy alloys (HEAs) are utilized in electrocatalysis applications owing to their diverse elemental composition, disordered elemental distribution, and the high solubility of each element, endowing them with excellent catalytic performance. The experiments were conducted using isoatomic FeNiCrMo HEA as a precursor, with a high-activity three-dimensional nanoporous structure rapidly synthesized via electrochemical one-step dealloying in a choline chloride-thiourea (ChCl-TU) deep eutectic solvent (DES). The results indicate that the dealloyed Fe20Co20Ni20Cr20Mo20 HEA mainly consists of two phases: face-centered cubic and σ phases. The imbalance in the distribution of elements in these two phases leads to quite different corrosion speeds with the FCC phase being preferentially corroded. Furthermore, synergistic electron coupling between surface atoms in the three-dimensional nanoporous structure strengthens the behavior of the oxygen evolution reaction (OER). At a current density of 40 mA cm-2, the overpotential after dealloying decreased to 370 mV, demonstrating excellent stability. The technique demonstrated in this work provides a novel approach to improve the catalytic activity of OER.

Electronic Control of the Position of the Pb Atom on the Surface of B8 Borozene in the PbB8 Cluster.

Spontaneous symmetry-breaking is common in chemical and physical systems. Here, we show that by adding an electron to the C7v PbB8 cluster, which consists of a planar B8 disk with the Pb atom situated along the C7 axis, the Pb atom spontaneously moves to the off-axis position in the PbB8- anion. Photoelectron spectroscopy of PbB8- reveals a broad ground-state transition and a large energy gap, suggesting a highly stable closed-shell PbB8 borozene complex and a significant geometry change upon electron detachment. Quantum chemistry calculations indicate that the lowest unoccupied molecular orbital of the C7v PbB8 cluster is a degenerate π orbital mainly consisting of the Pb 6px and 6py atomic orbitals. Occupation of one of the 6p orbitals spontaneously break the C7v symmetry in the anion due to the Jahn-Teller effect. The large amplitude of the position change of Pb in PbB8- relative to PbB8 is surprising owing to bonding interactions between the Pb 6p orbital with the π orbital of the B8 borozene.

Searching for stable copper borozene complexes in CuB7- and CuB8.

Copper has been shown to be an important substrate for the growth of borophenes. Copper-boron binary clusters are ideal platforms to study the interactions between copper and boron, which may provide insight about the underlying growth mechanisms of borophene on copper substrates. Here we report a joint photoelectron spectroscopy and theoretical study on two copper-doped boron clusters, CuB7- and CuB8-. Well resolved photoelectron spectra are obtained for the two clusters at different wavelengths and are used to understand the structures and bonding properties of the two CuBn- clusters. We find that CuB8- is a highly stable borozene complex, which possesses a half-sandwich structure with a Cu+ species interacting with the doubly aromatic η8-B82- borozene. The CuB7- cluster is found to consist of a terminal copper atom bonded to a double-chain B7 motif, but it has a low-lying isomer composed of a half-sandwich structure with a Cu+ species interacting with an open-shell η7-B72- borozene. Both ionic and covalent interactions are found to be possible in the binary Cu-B clusters, resulting in different structures.

Investigation of Pb-B Bonding in PbB2(BO)n- (n = 0-2): Transformation from Aromatic PbB2- to Pb[B2(BO)2]-/0 Complexes with BB Triple Bonds.

Boron has been found to be able to form multiple bonds with lead. To probe Pb-B bonding, here we report an investigation of three Pb-doped boron clusters, PbB2-, PbB3O-, and PbB4O2-, which are produced by a laser ablation cluster source and characterized by photoelectron spectroscopy and ab initio calculations. The most stable structures of PbB2-, PbB3O-, and PbB4O2- are found to follow the formula, [PbB2(BO)n]- (n = 0-2), with zero, one, and two boronyl ligands coordinated to a triangular and aromatic PbB2 core, respectively. The PbB2- cluster contains a BB double bond and two Pb-B single bonds. The coordination of BO is observed to weaken Pb-B bonding but strengthen the BB bond in [PbB2(BO)n]- (n = 1, 2). The anionic [PbB2(BO)2]- and its corresponding neutral closed-shell [PbB2(BO)2] contain a BB triple bond. A low-lying Y-shaped isomer is also observed for PbB4O2-, consisting of a central sp2 hybridized B atom bonded to two boronyl ligands and a PbB unit.

On the electronic structure and spin-orbit coupling of BiB from photoelectron imaging of cryogenically-cooled BiB- anion.

We report a study on the electronic structure and chemical bonding of the BiB molecule using high-resolution photoelectron imaging of cryogenically cooled BiB- anion. By eliminating all the vibrational hot bands, we can resolve the complicated detachment transitions due to the open-shell nature of BiB and the strong spin-orbit coupling. The electron affinity of BiB is measured to be 2.010(1) eV. The ground state of BiB- is determined to be 2Π(3/2) with a σ2π3 valence electron configuration, while the ground state of BiB is found to be 3Σ-(0+) with a σ2π2 electron configuration. Eight low-lying spin-orbit excited states [3Σ-(1), 1Δ(2), 1Σ+(0+), 3Π(2), 3Π(1), 1Π(1)], including two forbidden transitions, [3Π(0-) and 3Π(0+)], are observed for BiB as a result of electron detachment from the σ and π orbitals of BiB-. The angular distribution information from the photoelectron imaging is found to be critical to distinguish detachment transitions from the σ or π orbital for the spectral assignment. This study provides a wealth of information about the low-lying electronic states and spin-orbit coupling of BiB, demonstrating the importance of cryogenic cooling for obtaining well-resolved photoelectron spectra for size-selected clusters produced from a laser vaporization cluster source.

Bamboo charcoal affects soil properties and bacterial community in tea plantations.

Bamboo charcoal, a type of manufactured biochar, is produced by pyrolyzing bamboo residue under anoxic conditions. Its beneficial properties in absorption, catalyst support, and agricultural function have attracted significant attention; however, relatively few studies have examined its effects on the soil microbiota. In this study, we analyzed the effects of bamboo charcoal on soil physicochemical properties, enzymes, and microbial community structure in tea plantations and investigated the optimal amount of bamboo charcoal to be added to organic fertilizer. The results show that bamboo charcoal can further increase soil available nitrogen, total and available phosphorus and potassium, organic carbon content, pH, and urease activity. However, only the combined use of bamboo charcoal and organic fertilizer significantly increased total nitrogen, sucrase, and ß-glucosidase activities in the soil. Bamboo charcoal also significantly increased the Chao1 and Shannon indices of microbiota diversity in a concentration-dependent manner. The structure of the bacterial community changed significantly after the bamboo charcoal addition, with Proteobacteria, Actinobacteria, and Firmicutes increasing and Acidobacteria decreasing. This study provides fundamental insights into the suitability of bamboo charcoal application for the ecological remediation of diseased soils.

Cucurbitacin B Exerts Significant Antidepressant-Like Effects in a Chronic Unpredictable Mild Stress Model of Depression: Involvement of the Hippocampal BDNF-TrkB System.

BACKGROUND: Although depression has been a serious neuropsychiatric disorder worldwide, current antidepressants used in clinical practice have various weaknesses, including delayed onset and low rates of efficacy. Recently, the development of new antidepressants from natural herbal medicine has become one of the important research hotspots. Cucurbitacin B is a natural compound widely distributed in the Cucurbitaceae and Cruciferae families and has many pharmacological activities. The present study aimed to investigate whether cucurbitacin B possess antidepressant-like effects in mice. METHODS: The antidepressant-like effects of cucurbitacin B on mice behaviors were explored using the forced swim test, tail suspension test, open field test, sucrose preference test, and a chronic unpredictable mild stress model of depression together. Then, western blotting and immunofluorescence were used to examine the effects of cucurbitacin B on the brain-derived neurotrophic factor (BDNF)-tyrosine kinase B (TrkB) signaling cascade and neurogenesis in the hippocampus of mice. Furthermore, BDNF-short hairpin RNA, K252a, and p-chlorophenylalanine methyl ester were adopted together to determine the antidepressant mechanism of cucurbitacin B. RESULTS: It was found that administration of cucurbitacin B indeed produced notable antidepressant-like effects in mice, which were accompanied with significant promotion in both the hippocampal BDNF-TrkB pathway and neurogenesis. The antidepressant mechanism of cucurbitacin B involves the hippocampal BDNF-TrkB system but not the serotonin system. CONCLUSIONS: Cucurbitacin B has the potential to be a novel antidepressant candidate.

Association between triglyceride-glucose index and risk of end-stage renal disease in patients with type 2 diabetes mellitus and chronic kidney disease.

Aims: It has been suggested that the triglyceride-glucose (TyG) index is a novel and reliable surrogate marker of insulin resistance (IR). However, its relationship with the risk of end-stage renal disease (ESRD) in patients with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD) remains uncertain. Accordingly, we sought to examine the relationship between the TyG index and ESRD risk in patients with T2DM and CKD. Methods: From January 2013 to December 2021, 1,936 patients with T2DM and CKD hospitalized at Peking University Third Hospital (Beijing, China) were enrolled into the study. The formula for calculating the TyG index was ln[fasting triglyceride (mg/dL) × fasting blood glucose (mg/dL)/2]. ESRD was defined as an estimated glomerular filtration rate of less than 15 mL/min/1.73 m2 or the commencement of dialysis or renal transplantation. The relationship between the TyG index and ESRD risk was analyzed using Cox proportional hazard regression. Results: 105 (5.42%) participants developed ESRD over a mean follow-up of 41 months. The unadjusted analysis revealed a 1.50-fold (95% confidence interval [CI] 1.17-1.93; P = 0.001) increased risk for ESRD per one unit rise in the TyG index, and the positive association remained stable in the fully adjusted model (hazard ratio, 1.49; 95% CI, 1.12-1.99; P = 0.006). Analysis using restricted cubic spline revealed a significant positive association between the TyG index and ESRD risk. In addition, Kaplan-Meier analysis revealed significant risk stratification with a TyG index cutoff value of 9.5 (P = 0.003). Conclusion: In individuals with T2DM and CKD, a significant and positive association was shown between an elevated TyG index and the risk of ESRD. This conclusion provides evidence for the clinical importance of the TyG index for evaluating renal function decline in individuals with T2DM and CKD.

Photoelectron Spectroscopy and Theoretical Study of Di-Copper-Boron Clusters: Cu2B3- and Cu2B4.

Copper has been found to be able to mediate the formation of bilayer borophenes. Copper-boron binary clusters are ideal model systems to probe the copper-boron interactions, which are essential to understand the growth mechanisms of borophenes on copper substrates. Here, we report a joint photoelectron spectroscopy and theoretical study on two di-copper-doped boron clusters: Cu2B3- and Cu2B4-. Well-resolved photoelectron spectra are obtained, revealing the presence of a low-lying isomer in both cases. Theoretical calculations show that the global minimum of Cu2B3- (C2v, 1A1) contains a doubly aromatic B3- unit weakly interacting with a Cu2 dimer, while the low-lying isomer (C2v, 1A1) consists of a B3 triangle with the two Cu atoms covalently bonded to two B atoms at two vertexes. The global minimum of Cu2B4- (D2h, 2Ag) is found to consist of a rhombus B4 unit covalently bonded to the two Cu atoms at two opposite vertexes, whereas in the low-lying isomer (Cs, 2A'), one of the two Cu atoms is bonded to two B atoms.

The salt-inducible kinases inhibitor HG-9-91-01 exhibits antidepressant-like actions in mice exposed to chronic unpredictable mild stress.

Major depressive disorder is a frequently occurring neuropsychiatric disorder throughout the world. However, the limited and delayed therapeutic efficacy of monoaminergic medications has led to intensive research efforts to develop novel antidepressants. We have previously demonstrated that hippocampal salt-inducible kinase 2 (SIK2) plays a role in the pathogenesis of depression via regulating the downstream CREB-regulated transcription coactivator 1 (CRTC1)-cAMP response element-binding protein (CREB)-brain derived neurotrophic factor (BDNF) pathway. HG-9-91-01 is a potent and selective inhibitor of salt-inducible kinases (SIKs). The present study aims to explore whether HG-9-91-01 has antidepressant-like actions in male C57BL/6J mice. The chronic unpredictable mild stress (CUMS) model of depression, various behavioral tests, western blotting, co-immunoprecipitation, immunofluorescence, stereotactic infusion, and viral-mediated genetic knockdown were used together. It was found that hippocampal infusion of HG-9-91-01 induced significant antidepressant-like effects in the CUMS model, accompanied with preventing the enhancement of CUMS on the hippocampal SIK2 expression and cytoplasmic translocation of CRTC1. HG-9-91-01 treatment also reversed the decreasing effects of CUMS on the BDNF signaling cascade and adult neurogenesis in the hippocampus. Moreover, the antidepressant-like actions of HG-9-91-01 in mice required the hippocampal CRTC1-CREB-BDNF pathway. In conclusion, HG-9-91-01 has potential of being a novel antidepressant candidate.

Salt-inducible kinase 1-CREB-regulated transcription coactivator 1 signalling in the paraventricular nucleus of the hypothalamus plays a role in depression by regulating the hypothalamic-pituitary-adrenal axis.

Elucidating the molecular mechanism underlying the hyperactivity of the hypothalamic-pituitary-adrenal axis during chronic stress is critical for understanding depression and treating depression. The secretion of corticotropin-releasing hormone (CRH) from neurons in the paraventricular nucleus (PVN) of the hypothalamus is controlled by salt-inducible kinases (SIKs) and CREB-regulated transcription co-activators (CRTCs). We hypothesised that the SIK-CRTC system in the PVN might contribute to the pathogenesis of depression. Thus, the present study employed chronic social defeat stress (CSDS) and chronic unpredictable mild stress (CUMS) models of depression, various behavioural tests, virus-mediated gene transfer, enzyme-linked immunosorbent assay, western blotting, co-immunoprecipitation, quantitative real-time reverse transcription polymerase chain reaction, and immunofluorescence to investigate this connection. Our results revealed that both CSDS and CUMS induced significant changes in SIK1-CRTC1 signalling in PVN neurons. Both genetic knockdown of SIK1 and genetic overexpression of CRTC1 in the PVN simulated chronic stress, producing a depression-like phenotype in naive mice, and the CRTC1-CREB-CRH pathway mediates the pro-depressant actions induced by SIK1 knockdown in the PVN. In contrast, both genetic overexpression of SIK1 and genetic knockdown of CRTC1 in the PVN protected against CSDS and CUMS, leading to antidepressant-like effects in mice. Moreover, stereotactic infusion of TAT-SIK1 into the PVN also produced beneficial effects against chronic stress. Furthermore, the SIK1-CRTC1 system in the PVN played a role in the antidepressant actions of fluoxetine, paroxetine, venlafaxine, and duloxetine. Collectively, SIK1 and CRTC1 in PVN neurons are closely involved in depression neurobiology, and they could be viable targets for novel antidepressants.

The smallest 4f-metalla-aromatic molecule of cyclo-PrB2 - with Pr-B multiple bonds.

The concept of metalla-aromaticity proposed by Thorn-Hoffmann (Nouv. J. Chim. 1979, 3, 39) has been expanded to organometallic molecules of transition metals that have more than one independent electron-delocalized system. Lanthanides, with highly contracted 4f atomic orbitals, are rarely found in multiply aromatic systems. Here we report the discovery of a doubly aromatic triatomic lanthanide-boron molecule PrB2 - based on a joint photoelectron spectroscopy and quantum chemical investigation. Global minimum structural searches reveal that PrB2 - has a C 2v triangular structure with a paramagnetic triplet 3B2 electronic ground state, which can be viewed as featuring a trivalent Pr(III,f2) and B2 4-. Chemical bonding analyses show that this cyclo-PrB2 - species is the smallest 4f-metalla-aromatic system exhibiting σ and π double aromaticity and multiple Pr-B bonding characters. It also sheds light on the formation of the rare B2 4- tetraanion by the high-lying 5d orbitals of the 4f-elements, completing the isoelectronic B2 4-, C2 2-, N2, and O2 2+ series.

AuB8-: an Au-borozene complex.

Photoelectron spectroscopy and quantum chemistry studies are used to investigate the structure and bonding of AuB8-. Global minimum sturctural searches show that AuB8- possesses a chair-like structure, which can be viewed as Au+ bonded to the edge of the doubly-aromatic B82- borozene, Au+[η2-B82-]. Chemical bonding analyses reveal that the AuB8- is a novel borozene complex with unique Au-borozene bonding.

Boron-lead multiple bonds in the PbB2O- and PbB3O2- clusters.

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.

Monovalent lanthanide(I) in borozene complexes.

Lanthanide (Ln) elements are generally found in the oxidation state +II or +III, and a few examples of +IV and +V compounds have also been reported. In contrast, monovalent Ln(+I) complexes remain scarce. Here we combine photoelectron spectroscopy and theoretical calculations to study Ln-doped octa-boron clusters (LnB8-, Ln = La, Pr, Tb, Tm, Yb) with the rare +I oxidation state. The global minimum of the LnB8- species changes from Cs to C7v symmetry accompanied by an oxidation-state change from +III to +I from the early to late lanthanides. All the C7v-LnB8- clusters can be viewed as a monovalent Ln(I) coordinated by a η8-B82- doubly aromatic ligand. The B73-, B82-, and B9- series of aromatic boron clusters are analogous to the classical aromatic hydrocarbon molecules, C5H5-, C6H6, and C7H7+, respectively, with similar trends of size and charge state and they are named collectively as "borozenes". Lanthanides with variable oxidation states and magnetic properties may be formed with different borozenes.

Photoelectron Spectroscopy of Size-Selected Bismuth-Boron Clusters: BiBn- (n = 6-8).

Because of its low toxicity, bismuth is considered to be a "green metal" and has received increasing attention in chemistry and materials science. To understand the chemical bonding of bismuth, here we report a joint experimental and theoretical study on a series of bismuth-doped boron clusters, BiBn- (n = 6-8). Well-resolved photoelectron spectra are obtained and are used to understand the structures and bonding of BiBn- in conjunction with theoretical calculations. Global minimum searches find that all three BiBn- clusters have planar structures with the Bi atom bonded to the edge of the planar Bn moiety via two Bi-B σ bonds as well as π bonding by the 6pz orbital. BiB6- is found to consist of a double-chain B6 with a terminal Bi atom. Both BiB7- and BiB8- are composed of a Bi atom bonded to the planar global minima of the B7- and B8- clusters. Chemical bonding analyses reveal that BiB6- is doubly antiaromatic, whereas BiB7- and BiB8- are doubly aromatic. In the neutral BiBn (n = 6-8) clusters, except BiB6 which has a planar structure similar to the anion, the global minima of both BiB7 and BiB8 are found to be half-sandwich-type structures due to the high stability of the doubly aromatic B73- and B82- molecular wheel ligands.