The biocontrol potentials of rhizospheric bacterium Bacillus velezensis K0T24 against mulberry bacterial wilt disease.

Mulberry bacterial wilt disease, caused by Ralstonia pseudosolanacearum, is a devastating soil-borne disease in the silk-mulberry-related industry. In this study, through high-throughput sequencing, we compared the rhizosphere bacterial composition of the mulberry-resistant cultivar (K10) and susceptible cultivar (G12), confirming Bacillus as a genus-level biomarker for K10. Next, twelve Bacillus spp. isolates, derived from the rhizosphere of K10, were screened for their antagonistic activity against R. pseudosolanacearum. The isolate showing strong antagonism was identified as B. velezensis K0T24 and selected for further analysis. The fermentation supernatant of B. velezensis K0T24 significantly inhibited the growth of R. pseudosolanacearum (82.47%) and the expression of its pathogenic genes. Using B. velezensis K0T24 in mulberry seedlings also increased defense enzyme activities and achieved a control efficacy of up to 55.17% against mulberry bacterial wilt disease. Collectively, our findings demonstrate the potential of B. velezensis K0T24 in suppressing mulberry bacterial wilt disease.

Atmospheric Chemistry of NH2SO3H in Polluted Areas: An Unexpected Isomerization of NH2SO3H in Acid-Polluted Regions.

NH2SO3H is an effective nucleation agent for the formation of atmospheric aerosols and cloud particles. So, the ammonolysis of SO3 to form NH2SO3H without and with neutral (H2O) and basic (NH3) trace gases has been extensively investigated. However, the acidic trace gas X (X = H2SO4 and CH3SO3H)-assisted ammonolysis of SO3 is still up for debate. In this work, a comprehensive theoretical investigation of X-assisted ammonolysis of SO3 and its reverse reaction (the isomerization of NH2SO3H to form SO3-···NH3+) was carried out in the gas phase and at the air-water interface. The gas-phase results show that X-assisted isomerization of NH2SO3H to form SO3-···NH3+ is more energetically and kinetically favorable than its reverse reaction and the isomerization of NH2SO3H in the presence of H2O and NH3. Such unexpected findings revealed that gas-phase NH2SO3H is highly reactive in the presence of acidic trace gas in contrast to the high stability of NH2SO3H in neutral and basic conditions. At the air-water interface, the X-assisted isomerization reaction of NH2SO3H involves multiple water molecules. The loop structure of the reaction center (X···NH2SO3H···3H2O) promotes the transfer of protons in the water molecules to form the SO3-···NH3+ ion pair, which can then interact with several interfacial water molecules to form ammonium bisulfate. These interfacial reaction channels follow a stepwise mechanism and proceed at the picosecond time-scale. The findings of this study will contribute to a better understanding of the atmospheric behavior of NH2SO3H in polluted acidic trace gases.

An Interview Study of College Students' Health Emergency Literacy in the Context of COVID-19 Normalized Prevention and Control.

Objective: To explore the changes in college students' awareness of health protection under the normalization of COVID-19, and to seek its connection with the epidemic management in colleges and universities, so as to provide reference information for continuous health education activities and the cultivation of college students' health emergency literacy in colleges and universities. Methods: Qualitative interviews were used to understand the extent of health emergency literacy among college students enrolled in the context of a normalized epidemic and the factors associated with it that cause changes around a question outline. Results: The interviewees generally had a lax mentality in the late stage of the interview, the importance they attached to epidemic prevention and control decreased significantly, and the way to know about epidemic protection measures and other knowledge was mainly through the mass news media. All respondents affirm the importance of social software for outbreak prevention and control. All 17 interviewees were able to mention basic outbreak protection methods, but 15 of them showed inconsistent behavior in words and actions later. Conclusion: The vast majority of respondents' health emergency literacy appears to weaken in the late stages of epidemic normalization, and the effect of traditional approaches used by universities to improve college students' health emergency literacy is weak.

Study on the Potential for Stimulating Mulberry Growth and Drought Tolerance of Plant Growth-Promoting Fungi.

Drought stress often leads to heavy losses in mulberry planting, especially for fruits and leaves. Application of plant growth-promoting fungi (PGPF) endows various plant beneficial traits to overcome adverse environmental conditions, but little is known about the effects on mulberry under drought stress. In the present study, we isolated 64 fungi from well-growing mulberry trees surviving periodical drought stress, and Talaromyces sp. GS1, Pseudeurotium sp. GRs12, Penicillium sp. GR19, and Trichoderma sp. GR21 were screened out due to their strong potential in plant growth promotion. Co-cultivation assay revealed that PGPF stimulated mulberry growth, exhibiting increased biomass and length of stems and roots. Exogenous application of PGPF could alter fungal community structures in the rhizosphere soils, wherein Talaromyces was obviously enhanced after inoculation of Talaromyces sp. GS1, and Peziza was increased in the other treatments. Moreover, PGPF could promote iron and phosphorus absorption of mulberry as well. Additionally, the mixed suspensions of PGPF induced the production of catalase, soluble sugar, and chlorophyll, which in turn enhanced the drought tolerance of mulberry and accelerated their growth recovery after drought. Collectively, these findings might provide new insights into improving mulberry drought tolerance and further boosting mulberry fruit yields by exploiting interactions between hosts and PGPF.

Liraglutide Plus Dapagliflozin for High Uric Acid and Microalbuminuria in Diabetes Mellitus Complicated With Metabolic Syndrome.

Context: Diabetes mellitus (DM) represents an emerging epidemic, poses serious threats to human health, and can seriously compromise patients' quality of life (QoL). Currently, no cure exists for DM. Some studies have found that both liraglutide and dapagliflozin have great therapeutic potential in preventing and treating DM and its complications. Objective: The study aimed to examine the impact of liraglutide plus dapagliflozin on high uric acid (UA) and microalbuminuria (MAU) in patients with diabetes mellitus (DM) complicated with metabolic syndrome (MS). Design: The research team designed a randomized controlled trial. Setting: The study took place at the Second Affiliated Hospital of Nanjing Medical University in Nanjing, Jiangsu, China. Participants: Participants were 125 patients with DM complicated with MS who were treated in the outpatient clinic of the endocrinology department at the hospital between January 1, 2020 and December 31, 2021, with 68 in the intervention group and 57 in the control group. Intervention: The intervention and control groups both received 0.6 mg of liraglutide. The intervention group also received 5 mg of dapagliflozin once a day. The dosages were increased at one week after baseline based on the participant's condition. Outcome Measures: Therapeutic effects, glycolipid metabolism, inflammation, uric acid (UA), microalbuminuria (MAU), cardiac function, and quality of life (QoL) were compared between the two groups. Results: Postintervention, the clinical efficacy was significantly higher in the intervention group than in the control group. The intervention group had significantly lower glycolipid metabolism and inflammatory-factor levels than the control group UA and MAU had declined in both groups but were significantly lower in the intervention group. The left ventricular ejection fraction (LVEF) increased and the left ventricular end diastolic diameter (LVEDd) decreased in both groups, but the intervention group had significantly greater changes as compared with those in the control group. The intervention group was also superior to the control group in patients' QoL. Conclusions: Liraglutide plus dapagliflozin has highly therapeutic effect for patients with DM complicated with MS and can effectively reduce UA and MAU levels. The current research team will launch a more comprehensive analysis as soon as possible to obtain the most accurate results.

Li-N Interaction Induced Deep Eutectic Gel Polymer Electrolyte for High Performance Lithium-Metal Batteries.

As emerging eutectic mixtures, deep eutectic electrolytes (DEEs) show unique properties for Li-metal batteries (LMBs). However, the limited choice and inferior electrode compatibility hinder their further development in LMBs. Herein, we report a new 1,2-dimethylimidazole (DMIm)-based deep eutectic gel polymer electrolyte induced by Li-N interaction. We demonstrate that incorporating electron-withdrawing polyvinylidene difluoride (PVDF) polymer into the DMIm-based DEE changes the coordination environment of Li+ ions, leading to a high transference number of Li+ ions (0.65) and superior interface stability between the electrolyte and Li anode. The deep eutectic gel polymer electrolyte exhibits excellent non-flammability, high ionic conductivity (1.67 mS cm-1 at 30 °C), and high oxidation voltage (up to 4.35 V vs. Li/Li+ ). The Li||LFP cell based on the newly developed deep eutectic gel polymer electrolyte can achieve superior long-term cycling stability at a wide range of rates.

The impact of the endophytic bacterial community on mulberry tree growth in the Three Gorges Reservoir ecosystem, China.

Plant-associated microbes influence plant performance and may also impact biotic and abiotic stress tolerance. The microbiome of mulberry trees planted for ecological restoration in the hydro-fluctuation belt of the Three Gorges Reservoir Region, China, exhibited distinct patterns of localization. The endosphere exhibited lower α-diversity relative to the rhizosphere, but was more closely related to host growth status, especially in stem tissues. Pantoea was the predominant bacterial genus inhabiting the stems of two well-growing plants, while sequences identified as Pseudomonas and Pantoea were abundant in poorly growing plants. The complexity of the endophytic community was more connected to growth status in well-growing plants than it was in poorly growing plants. Among 151 endophytes cultured from collected samples of mulberry, 64 exhibited plant growth-promoting (PGP) potential in vitro and the majority of beneficial taxa were harvested from well-growing plants. Collectively, the present study indicates that the recruitment of beneficial endophytes may contribute to mulberry fitness under abiotic stress, and it provides a foundation for the development of a new strategy in vegetation restoration.

An Efficient and Stable Perovskite Solar Cell with Suppressed Defects by Employing Dithizone as a Lead Indicator.

The defects in perovskite films are one of the most non-negligible factors that can attenuate the performances of perovskite solar cell. This work fabricates defect-reduced perovskite film by using the lead indicator (dithizone) as an additive of perovskite functional layer. The dithizone can retard the crystallization rate of perovskite films, passivate the defects, and enhance the structure stability of perovskite by coordinating with lead atoms. As a result, the device doped with dithizone yields outstanding power conversion efficiency and stability.

Genomic and Functional Characterization of the Endophytic Bacillus subtilis 7PJ-16 Strain, a Potential Biocontrol Agent of Mulberry Fruit Sclerotiniose.

Bacillus sp. 7PJ-16, an endophytic bacterium isolated from a healthy mulberry stem and previously identified as Bacillus tequilensis 7PJ-16, exhibits strong antifungal activity and has the capacity to promote plant growth. This strain was studied for its effectiveness as a biocontrol agent to reduce mulberry fruit sclerotiniose in the field and as a growth-promoting agent for mulberry in the greenhouse. In field studies, the cell suspension and supernatant of strain 7PJ-16 exhibited biocontrol efficacy and the lowest disease incidence was reduced down to only 0.80%. In greenhouse experiments, the cell suspension (1.0 × 106 and 1.0 × 105 CFU/mL) and the cell-free supernatant (100-fold and 1000-fold dilution) stimulated mulberry seed germination and promoted mulberry seedling growth. In addition, to accurately identify the 7PJ-16 strain and further explore the mechanisms of its antifungal and growth-promoting properties, the complete genome of this strain was sequenced and annotated. The 7PJ-16 genome is comprised of two circular plasmids and a 4,209,045-bp circular chromosome, containing 4492 protein-coding genes and 116 RNA genes. This strain was ultimately designed as Bacillus subtilis based on core genome sequence analyses using a phylogenomic approach. In this genome, we identified a series of gene clusters that function in the synthesis of non-ribosomal peptides (surfactin, fengycin, bacillibactin, and bacilysin) as well as the ribosome-dependent synthesis of tasA and bacteriocins (subtilin, subtilosin A), which are responsible for the biosynthesis of numerous antimicrobial metabolites. Additionally, several genes with function that promote plant growth, such as indole-3-acetic acid biosynthesis, the production of volatile substances, and siderophores synthesis, were also identified. The information described in this study has established a good foundation for understanding the beneficial interactions between endophytes and host plants, and facilitates the further application of B. subtilis 7PJ-16 as an agricultural biofertilizer and biocontrol agent.

A photoelectron spectroscopy and quantum chemical study on ternary Al-B-O clusters: AlnBO2- and AlnBO2 (n = 2, 3).

Both B and Al have high oxygen affinity and their oxidation processes are highly exothermic, hinting at intriguing physical chemistry in ternary Al-B-O clusters. We report a combined photoelectron spectroscopy and density-functional study on the structural, electronic, and bonding properties of AlnBO2- and AlnBO2 (n = 2, 3) clusters. Ground-state vertical detachment energies (VDEs) are measured to be 2.83 and 2.24 eV for Al2BO2- and Al3BO2-, respectively. A weak isomer is also observed for Al3BO2- with a VDE of 1.31 eV. Coalescence-kick global searches allow the identification of candidate structures, confirmed via comparisons with experiment. The Al2BO2- anion is V-shaped in geometry, Cs (1A'), with an Al center connecting to OB and OAl terminals. It can be viewed alternatively as the fusion of BOAl and AlOAl by sharing an Al atom. Al3BO2- has a Cs (2A'') global minimum in which an Al2 dimer interacts with bridging boronyl (BO) and an OAl unit, as well as a low-lying C2v (2B2) isomer consisting of boronyl and OAl that are doubly bridged by two Al atoms. The BO2 block (linear O[double bond, length as m-dash]B[double bond, length as m-dash]O chain) is nonexistent in any of the anion and neutral species. Chemical bonding in these Al-B-O clusters is elucidated via canonical molecular orbitals and adaptive natural density partitioning. The cluster structures are also rationalized using the concept of sequential and competitive oxidation of B versus Al centers in AlnB. The first O atom prefers to oxidize B and form BO, whereas the second O atom has options to interact with a fresh Al/Aln/AlnB unit or a BO group. The former route wins thermodynamically, leading to the observed geometries.

Absolute Infrared Absorption Cross Section of the Simplest Criegee Intermediate Near 1285.7 cm-1.

The ν4 fundamental of the simplest Criegee intermediate, CH2OO, has been monitored with high-resolution infrared (IR) transient absorption spectroscopy under total pressures of 4-94 Torr. This IR spectrum provides an unambiguous identification of CH2OO and is potentially useful to determine the number density of CH2OO in various laboratory studies. Here we utilized an ultraviolet (UV) and IR coupled spectrometer to measure the UV and IR absorption spectra of CH2OO simultaneously; the absolute IR cross section can then be determined by using a known UV cross section. Due to significant pressure broadening in the studied pressure range, we integrated the IR absorption spectra between 1285.2 and 1286.4 cm-1 (covering the Q branch), and then we converted this integrated absorbance to the absolute integral IR cross section of CH2OO (for the Q branch); its absolute value is (3.7 ± 0.6) × 10-19 cm·molecule-1 or 2.2 ± 0.4 km·mol-1. The whole rotational band (P, Q, and R branches) can be adequately simulated by using the precise spectroscopic parameters from the literature, yielding the absolute integral IR cross section (full ν4 band) to be 19.2 ± 3.5 km·mol-1. For a practical detection of CH2OO, this work also reports the peak cross section as a function of total pressure (4-94 Torr O2). At low pressure (≤4 Torr), where the pressure broadening is insignificant, the absorption cross section of the highest peak is (6.2 ± 0.9) × 10-18 cm2·molecule-1 (at the system line width of 0.004 cm-1 fwhm).

CoQ0-induced mitochondrial PTP opening triggers apoptosis via ROS-mediated VDAC1 upregulation in HL-60 leukemia cells and suppresses tumor growth in athymic nude mice/xenografted nude mice.

Coenzyme Q (CoQ) analogs with variable numbers of isoprenoid units have been demonstrated as anticancer and antioxidant/pro-oxidant molecules. This study examined the in vitro and in vivo antitumor and apoptosis activities of CoQ0 (2,3-dimethoxy-5-methyl-1,4-benzoquinone, zero isoprenoid side-chains) through upregulation of the Voltage-dependent anion channel 1 (VDAC1) signaling pathway on human promyelocytic leukemia. CoQ0 (0-40 µg/mL) treatment significantly reduced HL-60 cell viability, and up-regulated mitochondrial VDAC1 expression. CoQ0 treatment triggers intracellular ROS generation, calcium release, ΔΨm collapse and PTP opening in HL-60 cells. CoQ0 treatment induced apoptosis, which was associated with DNA fragmentation, cytochrome c release, caspase-3 and PARP activation, and Bax/Bcl-2 dysregulation. Annexin V-PI staining indicated that CoQ0 promotes late apoptosis. Furthermore, the blockade of CoQ0-induced ROS production by antioxidant NAC pretreatment substantially attenuated CoQ0-induced apoptosis. The activation of p-GSK3ß expression, cyclophilin D inhibition, and p53 activation through ROS are involved in CoQ0-induced HL-60 apoptotic cell death. Notably, ROS-independent p38 activation is involved in CoQ0-mediated apoptosis in HL-60 cells. In addition, the silencing of VDAC1 also prevented CoQ0-induced mitochondrial translocation of Bax, activation of caspase-3, and reduction in Bcl-2. Intriguingly, VDAC1 silencing did not prevent ROS production induced by CoQ0, which in turn indicates that CoQ0 induced ROS-mediated VDAC1 and then mitochondrial apoptosis in HL-60 cells. In vivo results revealed that CoQ0 is effective in delaying tumor incidence and reducing the tumor burden in HL-60-xenografted nude mice. Taken together, CoQ0 could be a promising anticancer agent for the treatment of human promyelocytic leukemia through upregulation of VDAC1 signaling pathways.

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 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.

Chemical bonding and dynamic fluxionality of a B15(+) cluster: a nanoscale double-axle tank tread.

A planar, elongated B15(+) cationic cluster is shown to be structurally fluxional and functions as a nanoscale tank tread on the basis of electronic structure calculations, bonding analyses, and molecular dynamics simulations. The outer B11 peripheral ring behaves like a flexible chain gliding around an inner B4 rhombus core, almost freely at the temperature of 500 K. The rotational energy barrier is only 1.37 kcal mol(-1) (0.06 eV) at the PBE0/6-311+G* level, further refined to 1.66 kcal mol(-1) (0.07 eV) at the single-point CCSD(T)/6-311G*//CCSD/6-311G* level. Two soft vibrational modes of 166.3 and 258.3 cm(-1) are associated with the rotation, serving as double engines for the system. Bonding analysis suggests that the "island" electron clouds, both σ and π, between the peripheral ring and inner core flow and shift continuously during the intramolecular rotation, facilitating the dynamic fluxionality of the system with a small rotational barrier. The B15(+) cluster, roughly 0.6 nm in dimension, is the first double-axle nanoscale tank tread equipped with two engines, which expands the concepts of molecular wheels, Wankel motors, and molecular tanks.

Structures and chemical bonding of B3O3 (-/0) and B3O3H(-/0): A combined photoelectron spectroscopy and first-principles theory study.

We present a combined photoelectron spectroscopy and first-principles theory study on the structural and electronic properties and chemical bonding of B3O3 (-/0) and B3O3H(-/0) clusters. The concerted experimental and theoretical data show that the global-minimum structures of B3O3 and B3O3H neutrals are very different from those of their anionic counterparts. The B3O3 (-) anion is characterized to possess a V-shaped OB-B-BO chain with overall C2 v symmetry (1A), in which the central B atom interacts with two equivalent boronyl (B≡O) terminals via B-B single bonds as well as with one O atom via a B=O double bond. The B3O3H(-) anion has a Cs (2A) structure, containing an asymmetric OB-B-OBO zig-zag chain and a terminal H atom interacting with the central B atom. In contrast, the C2 v (1a) global minimum of B3O3 neutral contains a rhombic B2O2 ring with one B atom bonded to a BO terminal and that of neutral B3O3H (2a) is also of C2 v symmetry, which is readily constructed from C2 v (1a) by attaching a H atom to the opposite side of the BO group. The H atom in B3O3H(-/0) (2A and 2a) prefers to interact terminally with a B atom, rather than with O. Chemical bonding analyses reveal a three-center four-electron (3c-4e) π hyperbond in the B3O3H(-) (2A) cluster and a four-center four-electron (4c-4e) π bond (that is, the so-called o-bond) in B3O3 (1a) and B3O3H (2a) neutral clusters.

Observation and characterization of the smallest borospherene, B28(-) and B28.

Free-standing boron nanocages or borospherenes have been observed recently for B40(-) and B40. There is evidence that a family of borospherenes may exist. However, the smallest borospherene is still not known. Here, we report experimental and computational evidence of a seashell-like borospherene cage for B28(-) and B28. Photoelectron spectrum of B28(-) indicated contributions from different isomers. Theoretical calculations showed that the seashell-like B28(-) borospherene is competing for the global minimum with a planar isomer and it is shown to be present in the cluster beam, contributing to the observed photoelectron spectrum. The seashell structure is found to be the global minimum for neutral B28 and the B28(-) cage represents the smallest borospherene observed to date. It is composed of two triangular close-packed B15 sheets, interconnected via the three corners by sharing two boron atoms. The B28 borospherene was found to obey the 2(n + 1)(2) electron-counting rule for spherical aromaticity.

On the structure and bonding in the B4O4(+) cluster: a boron oxide analogue of the 3,5-dehydrophenyl cation with π and σ double aromaticity.

Boron oxide clusters offer intriguing molecular models for the electron-deficient system, in which the boronyl (BO) group plays a key role and the interplay between the localized BO triple bond and the multicenter electron delocalization dominates the chemical bonding. Here we report the structural, electronic, and bonding properties of the B4O4(+) cationic cluster on the basis of unbiased Coalescence Kick global-minimum searches and first-principles electronic structural calculations at the B3LYP and single-point CCSD(T) levels. The B4O4(+) cluster is shown to possess a Cs (1, (2)A') global minimum. It represents the smallest boron oxide species with a hexagonal boroxol (B3O3) ring as the core, terminated by a boronyl group. Chemical bonding analyses reveal double (π and σ) aromaticity in Cs B4O4(+), which closely mimics that in the 3,5-dehydrophenyl cation C6H3(+) (D3h, (1)A1'), a prototypical molecule with double aromaticity. Alternative D2h (2, (2)B3g) and C2v (3, (2)A1) isomeric structures of B4O4(+) are also analyzed, which are relevant to the global minima of B4O4 neutral and B4O4(-) anion, respectively. These three structural motifs vary drastically in terms of energetics upon changing the charge state, demonstrating an interesting case in which every electron counts. The calculated ionization potentials and electron affinities of the three corresponding neutral isomers are highly uneven, which underlie the conformational changes in the B4O4(+/0/-) series. The current work presents the smallest boron oxide species with a boroxol ring, establishes an analogy between boron oxides and the 3,5-dehydrophenyl cation, and enriches the chemistry of boron oxides and boronyls.

Ternary B2X2H2 (X = O and S) rhombic clusters and their potential use as inorganic ligands in sandwich-type (B2X2H2)2Ni complexes.

Based upon global searches and electronic structure calculations at the B3LYP and CCSD(T) levels, we present the global-minimum structures of two ternary B-O-H and B-S-H rhombic clusters: D2h B2O2H2 (1, (1)Ag) and C2v B2S2H2 (2, (1)A1). Both species feature a B2X2 (X = O or S) four-membered ring as the core, with two H atoms attached terminally. The former cluster is perfectly planar, whereas the latter undergoes a slight butterfly distortion. Bonding analyses reveal a four-center four-electron (4c-4e) o-bond in these clusters, which are 4π systems in a nonbonding/bonding combination, in contrast to an antibonding/bonding combination in a classical 4π antiaromatic hydrocarbon such as cyclobutadiene (C4H4). Clusters 1 and 2 are considered to be aromatic. The present results also help elucidate the bonding nature in the relevant heteroatomic ring B2N2H4 system and suggest that it is not appropriate to consider B2N2H4 as an inorganic cyclobutadiene, a conception that has been in existence in the literature for over 40 years. The electronic properties of the global-minimum clusters 1 and 2 are predicted. It is shown that B2O2H2 (1) and B2S2H2 (2) may serve as effective inorganic ligands to form sandwich-type transition metal complexes, such as D2d [B2O2H2]2Ni (3) and D2d [B2S2H2]2Ni (4).

Planar dicyclic B6S6, B6S6(-), and B6S6(2-) clusters: boron sulfide analogues of naphthalene.

Inorganic analogues of hydrocarbons or polycyclic aromatic hydrocarbons (PAHs) are of current interest in chemistry. Based upon global structural searches and B3LYP and CCSD(T) calculations, we present herein the perfectly planar dicyclic boron sulfide clusters: D2h B6S6 (1, (1)Ag), D2h B6S6(-) (2, (2)B3u), and D2h B6S6(2-) (3, (1)Ag). These are the global minima of the systems, being at least 0.73, 0.81, and 0.53 eV lower in energy, respectively, than their alternative isomers at the CCSD(T) level. The D2h structures feature twin B3S2 five-membered rings, which are fused together via a B2 unit and terminated by two BS groups. Bonding analyses show that the closed-shell B6S6(2-) (3) cluster possesses 10 delocalized π electrons, closely analogous to the bonding pattern of the aromatic naphthalene C10H8. The B6S6(-) (2) and B6S6 (1) species are readily obtained upon removal of one or two π electrons from B6S6(2-) (3). The results build a new analogous relationship between boron sulfide clusters and their PAH counterparts. The B6S6(-) (2) monoanion and B6S6(2-) (3) dianion can be effectively stabilized in neutral LiB6S6 and Li2B6S6 salts, respectively.