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1.
Angew Chem Int Ed Engl ; 63(33): e202406089, 2024 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-38781000

RESUMO

Silyl anions have garnered significant attention due to their synthetic abilities. However, previously reported silyl anions have been limited to either trigonal-pyramidal or trigonal-planar geometries, which confine them primarily as nucleophiles in substitution reactions. Herein, we report the isolation of the unprecedented T-shaped planar silyl anion salt 2 by employment of a geometrically constrained triamido pincer ligand. Theoretical calculations disclosed that the silicon centre in 2 possesses both a lone pair of electrons and an empty 3pz orbital. In addition to nucleophilic substitution reactions with Ph3PAuCl and W(CO)6, 2 readily undergoes oxidative additions with CO2 and 2,6-dimethylphenylisonitrile at room temperature. Furthermore, under mild conditions, compound 2 cleaves Csp2-H, Csp2-H, and H-H bonds in 1,2,4,5-tetrafluorobenzene, an intramolecular iPr group, and dihydrogen, representing the first examples of C-H and H-H activations mediated by a silyl anion, respectively. This work unveils new reactivity of silyl anions owing to the non-classical geometry and electronic structure.

2.
Chem Soc Rev ; 51(14): 5930-5973, 2022 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-35770612

RESUMO

Radical species are significant in modern chemistry. Their unique chemical bonding and novel physicochemical properties play significant roles not only in fundamental chemistry, but also in materials science. Main group element radicals are usually transient due to their high reactivity. Highly stable radicals are often stabilized by π-delocalization, sterically demanding ligands, carbenes and weakly coordinating anions in recent years. This review presents the recent advances in the synthesis, characterization, reactivity and physical properties of isolable main group element radicals.


Assuntos
Ânions , Ânions/química , Ligantes
3.
Angew Chem Int Ed Engl ; 62(36): e202308467, 2023 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-37395499

RESUMO

This report unveils an advancement in the formation of a Lewis superacid (LSA) and an organic superbase by the geometrical deformation of an organoboron species towards a T-shaped geometry. The boron dication [2]2+ supported by an amido diphosphine pincer ligand features both a large fluoride ion affinity (FIA>SbF5 ) and hydride ion affinity (HIA>B(C6 F5 )3 ), which qualifies it as both a hard and soft LSA. The unusual Lewis acidic properties of [2]2+ are further showcased by its ability to abstract hydride and fluoride from Et3 SiH and AgSbF6 respectively, and effectively catalyze the hydrodefluorination, defluorination/arylation, as well as reduction of carbonyl compounds. One and two-electron reduction of [2]2+ affords stable boron radical cation [2]⋅+ and borylene 2, respectively. The former species has an extremely high spin density of 0.798e at the boron atom, whereas the latter compound has been demonstrated to be a strong organic base (calcd. pKBH + (MeCN)=47.4) by both theoretical and experimental assessment. Overall, these results demonstrate the strong ability of geometric constraining to empower the central boron atom.

4.
Inorg Chem ; 61(29): 11137-11142, 2022 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-35815522

RESUMO

Anionic oxoboranes and neutral iminoboranes, which are isoelectronic to ketones and alkynes, respectively, have attracted much attention because of their unique structures and various reactivity. However, acid/base-free oxoboranes and iminoboranes are still limited, and readily accessible examples with diverse electronic and steric characteristics are highly desirable. Herein, we report the first syntheses of the acyclic anionic oxoborane 2 and iminoborane 4 bearing two boryl ligands, both of which are acid/base-free. Spectroscopic analysis, X-ray crystallography, and theoretical calculations reveal that 2 and 4 possess a polarized terminal B═O double bond and central B≡N triple bond, respectively.

5.
Dermatol Ther ; 33(6): e14483, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33128423

RESUMO

Lactoferrin (LF) is a monomer glycoprotein in the mammalian colostrum that has multiple biological activities and a high affinity for iron ions. Not only does it have strong antibacterial activity, it also can regulate the release of cytokines in inflammatory areas, activate immune cells, and inhibit inflammatory diseases caused by non-pathogenic bacteria and the development of tumors. However, the anti-inflammatory mechanism of LF in inflammatory skin diseases induced by Propionibacterium acnes (P. acnes) has not been elucidated in vitro and in vivo. In this study, we investigated the effects of LF on the generation of inflammatory cytokines in HaCaT cells induced by heat-killed P. acnes. The expression of pro-inflammatory cytokines IL-8 increased after induction of HaCaT by heat-killed P. acnes, but it decreased significantly after LF treatment. Western blotting was used to examine the levels of TLR2, nuclear factor (NF) κB and intercellular cell adhesion molecule 1 protein induced by P. acnes in HaCaT cells, and the results showed that the levels were inhibited by LF. In addition, activated P. acnes (1 × 107 CFU/mL) was injected into the ears of experimental mice, which induced inflammation 24 hours after the injection. However, immunohistochemical analysis showed a significant reduction in the inflammatory response after LF treatment in the right ear relative to the untreated left ear, and the same result was seen with western blotting. In summary, this study revealed the treatment effect of LF on P. acnes-induced inflammation, thus providing support for the anti-acne properties of LF.


Assuntos
Acne Vulgar , Propionibacterium acnes , Acne Vulgar/tratamento farmacológico , Animais , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Inflamação/tratamento farmacológico , Lactoferrina/uso terapêutico , Camundongos
6.
Chem Soc Rev ; 48(13): 3613-3659, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30977491

RESUMO

Most of the chemical and biological processes involving the fixation and transformation of small molecules have long been exclusive for metal complexes. Meanwhile, the last decades have seen a significant advance in main group chemistry that mimics transition-metal complexes, among which various boron-containing systems have been successful in mediating the small molecule activation. In this review, we focus on boron-containing heterocycles enabling the activation of σ- and π-bonds in small molecules, in conjunction with the proposed mechanisms.

7.
Angew Chem Int Ed Engl ; 59(29): 11794-11799, 2020 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-32304152

RESUMO

Although diradicals and azaacenes have been greatly attractive in fundamental chemistry and functional materials, the isolable diradical dianions of azaacenes are still unknown. Herein, we describe the first isolation of pyrene-fused azaacene diradical dianion salts [(18-c-6)K(THF)2 ]+ [(18-c-6)K]+ ⋅12-.. and [(18-c-6)K(THF)]2+ ⋅22-.. by reduction of the neutral pyrene-fused azaacene derivatives 1 and 2 with excess potassium graphite in THF in the presence of 18-crown-6. Their electronic structures were investigated by various experiments, in conjunction with theoretical calculations. It was found that both dianions are open-shell singlets in the ground state and their triplet states are thermally readily accessible owing to the small singlet-triplet energy gap. This work provides the first examples of crystalline diradical dianions of azaacenes with considerable diradical character.

8.
J Am Chem Soc ; 141(35): 13729-13733, 2019 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-31418571

RESUMO

A newly developed annulated 5-chlorinated 1,3,2,5-diazadiborinine derivative (4) selectively activates a C-H bond of benzene (C6H6) and 1,3-di(trifluoromethyl)benzene, as well as a C-F bond in partially fluorinated arenes, to furnish borylation products under catalyst-, metal-, and irradiation-free conditions. Moreover, 4 readily undergoes a reversible dearomative coupling reaction with polycyclic aromatic hydrocarbons to afford diboration products. The latter represents the first reversible intermolecular dearomative diboration of arenes.

9.
Angew Chem Int Ed Engl ; 57(26): 7846-7849, 2018 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-29704290

RESUMO

An annulated 1,3,2,5-diazadiborinine with 14 π electrons has been synthesized and fully characterized. Experimental and computational studies revealed that this compound features a rather small HOMO-LUMO gap, which leads to enhanced reactivity towards small molecules. Thus, the 1,3,2,5-diazadiborinine readily cleaves the H-H bond of dihydrogen and an N-H bond of ammonia under mild conditions. Moreover, it reacts with 2,6-dimethylphenylisonitrile in a [4+1] cycloaddition at room temperature.

10.
Angew Chem Int Ed Engl ; 54(5): 1634-7, 2015 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-25504531

RESUMO

A series of bis[N,N-di-(4-methoxylphenyl)amino]arene dications 1(2+) -3(2+) have been synthesized and characterized. Their electronic structures were investigated by various experiments assisted by theoretical calculations. It was found that they are singlets in the ground state and that their diradical character is dependent on the bridging moiety. 3(2+) has a smaller singlet-triplet energy gap and its excited triplet state is thermally readily accessible. The work provides a nitrogen analogue of Thiele's hydrocarbon with considerable diradical character.

11.
J Am Chem Soc ; 136(17): 6251-4, 2014 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-24731124

RESUMO

Two phosphorus-containing four-membered ring radical cations 1(•+) and 2(•+) have been isolated and characterized by UV-vis absorption spectroscopy, electron paramagnetic resonance (EPR), and single-crystal X-ray diffraction. Compared with neutral molecules 1 and 2, radical 1(•+) has elongated P-P bonds and more pyramidalized phosphorus atoms, while shortened P-Nring distances and larger angles around phosphorus centers are observed for 2(•+). EPR studies indicate that for 1(•+) spin density mainly resides on the exocyclic nitrogen atoms with very minor contribution from endocyclic phosphorus atoms, while the situation is opposite for 2(•+). Such an inverse spin density distribution is controlled by the exocyclic substituents, which is supported by DFT calculations.

12.
Angew Chem Int Ed Engl ; 53(11): 2857-61, 2014 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-24497377

RESUMO

Three bis(triarylamine) dications were isolated by using weakly coordinating anions. Their electronic structures in the ground state were investigated by various experiments in conjunction with theoretical calculations. The ground-state electronic structures of these species were tunable by substituent effects, with two of them as closed-shell singlets and one of them as an open-shell singlet in the solid state. The excited state of the latter is thermally accessible, indicated by EPR and SQUID measurements. The work provides a new and stable diradicaloid structure motif with an excited triplet sate.

13.
Medicine (Baltimore) ; 103(29): e39071, 2024 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-39029035

RESUMO

INTRODUCTION: Acquired reactive perforating collagenosis (ARPC) is a rare perforating skin disease with unclear pathogenesis, often leading to misdiagnosis. Utilizing noninvasive skin microscopy improves diagnostic accuracy while reducing misdiagnosis rates. PATIENT CONCERNS: Given its association with systemic diseases, comprehensive examinations are crucial for early detection of related diseases such as tumors. Clinically, it still lacks standardized guidelines for the treatment. Clinical treatment is mostly based on symptomatic treatment. Oral administration of pregabalin capsules can significantly relieve itching symptoms, and narrow-wave ultraviolet irradiation can accelerate the recovery of skin lesions. DIAGNOSIS: Dermoscopy and skin biopsy was used to confirm this case was ARPC. INTERVENTIONS: Treatment was based on oral administration of 20 mg prednisone, 1 tablet of loratadine, 1 tablet of pregabalin in the morning and evening, and external application of halomethasone ointment. OUTCOMES: Itching symptoms were significantly relieved. CONCLUSION: This case report demonstrates that clinical dermoscopy can improve the diagnosis rate of ARPC, and pregabalin capsules can significantly relieve itching symptoms.


Assuntos
Doenças do Colágeno , Humanos , Doenças do Colágeno/diagnóstico , Doenças do Colágeno/patologia , Prurido/etiologia , Prurido/tratamento farmacológico , Pregabalina/uso terapêutico , Dermoscopia/métodos , Feminino , Dermatopatias/diagnóstico , Dermatopatias/tratamento farmacológico , Masculino , Pele/patologia , Pessoa de Meia-Idade
14.
J Am Chem Soc ; 135(15): 5561-4, 2013 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-23550780

RESUMO

Salts containing tetraaryldiphosphine radical cation 1(•+) and dication 1(2+) have been isolated and structurally characterized. Radical 1(•+) has a relaxed pyramidal geometry, while dication 1(2+) prefers a planar, olefin-like geometry with a two-electron π bond. The alteration of the geometries of the tetraaryldiphosphine upon oxidation is rationalized by the nature of the bonding. The EPR spectrum showed that the spin density of radical 1(•+) is mainly localized on phosphorus atoms, which is supported by theoretical calculation.

15.
J Cosmet Dermatol ; 22(4): 1361-1368, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36700382

RESUMO

BACKGROUND: The aim of this study was to explore the anti-inflammatory and anti-lipid effects of lactoferrin on SZ95 human sebaceous gland cells and mouse model of acne. METHODS: SZ95 cells were co-cultured with different concentrations of lactoferrin, and cell viability was determined using the 2,5-diphenyl-2H-tetrazolium bromide method. Oil red O and Nile red staining were performed to determine the lipid content. The mRNA expression of genes related to lipid metabolism (sterol regulatory element-binding protein-1 [SREBP-1], fatty acid synthase [FAS], stearoyl-CoA desaturase-1 [SCD-1], fatty acid desaturase 2 [FADS2]) and inflammation (interleukin-8 [IL-8]) was determined by reverse transcription-polymerase chain reaction. An acne mouse model was established using injection of P. acnes on the backs of mice. The proliferation and apoptosis of sebaceous gland cells were examined by immunohistochemistry against proliferating cell nuclear antigen (PCNA) and TUNEL staining, respectively. Western blotting was used to detect FADS2 and CXCL15 protein expression. RESULTS: Lactoferrin treatment at 10-500 µg/ml significantly decreased the lipid content, as revealed by the oil red O and Nile red staining. It also attenuated the increase of mRNA expression of SREBP-1, FAS, SCD-1, FADS2, and IL-8 in insulin-treated SZ95 cells. Moreover, lactoferrin treatment at the doses of 1-50 mg/mouse significantly reduced the inflammation and lipid production in the mouse model of acne. Also, the number of sebaceous gland cells was significantly reduced, and apoptosis was significantly increased by lactoferrin treatment in the mice. Mechanically, the levels of FADS2 and CXCL15 proteins in tissues were significantly decreased after lactoferrin treatment in the model mice. CONCLUSION: Our results demonstrate the potential of lactoferrin against sebogenesis, sebaceous gland inflammation in acne.


Assuntos
Acne Vulgar , Lactoferrina , Glândulas Sebáceas , Animais , Humanos , Camundongos , Acne Vulgar/metabolismo , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Interleucina-8/metabolismo , Lactoferrina/farmacologia , Lipogênese/fisiologia , RNA Mensageiro/metabolismo , Glândulas Sebáceas/metabolismo , Proteína de Ligação a Elemento Regulador de Esterol 1/genética , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Proteína de Ligação a Elemento Regulador de Esterol 1/farmacologia
16.
Chem Commun (Camb) ; 59(15): 2161-2164, 2023 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-36727589

RESUMO

The heaviest pnictogen-dipyrromethenes DPMPnCl2 (Pn = Sb, 3; Bi 4), which are direct analogues of boron-dipyrromethene (BODIPY), have been readily prepared and isolated as crystalline solids. Both compounds display green photoluminescence with small full widths at half maximum in toluene. Moreover, the reduction of 3 with sodium metal afforded the cyclic dicoordinate stibinidene 5.

17.
Chem Sci ; 14(13): 3548-3553, 2023 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-37006684

RESUMO

Chichibabin's hydrocarbon and viologens are among the most famous diradicaloids and organic redox systems, respectively. However, each has its own disadvantages: the instability of the former and its charged species, and the closed-shell nature of the neutral species derived from the latter, respectively. Herein, we report that terminal borylation and central distortion of 4,4'-bipyridine allow us to readily isolate the first bis-BN-based analogues (1 and 2) of Chichibabin's hydrocarbon with three stable redox states and tunable ground states. Electrochemically, both compounds exhibit two reversible oxidation processes with wide redox ranges. One- and two-electron chemical oxidations of 1 afford the crystalline radical cation 1˙+ and dication 12+, respectively. Moreover, the ground states of 1 and 2 are tunable with 1 as a closed-shell singlet and the tetramethyl-substituted 2 as an open-shell singlet, the latter of which could be thermally excited to its triplet state because of the small singlet-triplet gap.

18.
Chem Sci ; 14(21): 5722-5727, 2023 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-37265721

RESUMO

Isolable T-shaped planar pnictogen compounds R3Pn were reported more than three decades ago and have been attracting burgeoning interest in recent years; T-shaped planar group 14 anions, isoelectronic to R3Pn, however, are still unknown. Herein, we report the synthesis, full characterization, and reactivity of the first crystalline T-shaped planar group 14 anion 4 bearing a trinitrogen pincer ligand. DFT calculations indicate that the tricoordinate germanium center features both an unoccupied 4p orbital and two lone pairs of electrons. Its electron-rich nature allows for the nucleophilic attack on the methyl iodine giving methyl-substituted complex 5 and facile oxidation of the germanium center by elemental sulfur and selenium to furnish unpresented organic anions bearing terminal Ge[double bond, length as m-dash]Ch (Ch = S or Se) double bonds.

19.
Nanoscale ; 15(12): 5909-5918, 2023 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-36876891

RESUMO

Non-thermal plasma (NTP) degradation of volatile organic compounds (VOCs) into CO2 and H2O is a promising strategy for addressing ever-growing environment pollution. However, its practical implementation is hindered by low conversion efficiency and emissions of noxious by-products. Herein, an advanced low-oxygen-pressure calcination process is developed to fine-tune the oxygen vacancy concentration of MOF-derived TiO2 nanocrystals. Vo-poor and Vo-rich TiO2 catalysts were placed in the back of an NTP reactor to convert harmful ozone molecules into ROS that decompose VOCs via heterogeneous catalytic ozonation processes. The results indicate that Vo-TiO2-5/NTP with the highest Vo concentration exhibited superior catalytic activity in the degradation of toluene compared to NTP-only and TiO2/NTP, achieving a maximum 96% elimination efficiency and 76% COx selectivity at an SIE of 540 J L-1. Mechanistic analysis reveals that the 1O2, ˙O2- and ˙OH species derived from the activation of O3 molecules on Vo sites contribute to the decomposition of toluene over the Vo-rich TiO2 surface. With the aid of advanced characterization and density functional theory calculations, the roles of oxygen vacancies in manipulating the synergistic capability of post-NTP systems were explored, and were attributed to increased O3 adsorption ability and enhanced charge transfer dynamics. This work presents novel insights into the design of high-efficiency NTP catalysts structured with active Vo sites.

20.
Inorg Chem ; 51(24): 13162-70, 2012 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-23066635

RESUMO

Reaction of L(0)NiBr(2) with 2 equiv of NaH yielded the Ni(II) hydride complex [(L(•-))Ni(µ-H)(2)Ni(L(•-))] (1) (L = [(2,6-iPr(2)C(6)H(3))NC(Me)](2); L(0) represents the neutral ligand, L(•-) is its radical-anionic form, and L(2-) denotes the dianion) in good yield. Stepwise reduction of complex 1 led to a series of nickel hydrides. Reduction of 1 with 1 equiv of sodium metal afforded a singly reduced species [Na(DME)(3)][(L(•-))Ni(µ-H)(2)Ni(L(•-))] (2a) (DME = 1,2-dimethoxyethane), which contains a mixed-valent core [Ni(µ-H)(2)Ni](+). With 2 equiv of Na a doubly reduced species [Na(DME)](2)[L(2-)Ni(µ-H)(2)NiL(2-)] (3a) was obtained, in which each monoanion (L(•-)) in the precursor 1 has been reduced to L(2-). By using potassium as the reducing agent, two analogous species [K(DME)(4)][(L(•-))Ni(µ-H)(2)Ni(L(•-))] (2b) and [K(DME)](2)[L(2-)Ni(µ-H)(2)NiL(2-)] (3b) were obtained. Further treatment of 3b with 2 equiv of K led to a trinuclear complex [K(DME)(THF)](2)K(2)[L(2-)Ni(µ-H)(2)Ni(µ-H)(2)NiL(2-)] (4), which contains one Ni(II) and two Ni(I) centers with a triplet ground state. When 1 and 3a were warmed in toluene or benzene, respectively, three reverse-sandwich dinickel complexes, [(L(•-))Ni(µ-η(3):η(3)-C(7)H(8))Ni(L(•-))] (5) and [Na(DME)](2)[L(2-)Ni(µ-η(3):η(3)-C(6)H(5)R)NiL(2-)] (6: R = CH(3); 7: R = H), were isolated. Reaction of 1 with Me(3)SiN(3) gave the N(3)-bridged complex [(L(•-))Ni(µ-η(1)-N(3))(2)Ni(L(•-))] (8). The crystal structures of complexes 1-8 have been determined by X-ray diffraction, and their electronic structures have been fully studied by EPR/NMR spectroscopy.

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