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1.
Angew Chem Int Ed Engl ; : e202408142, 2024 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-38818643

RESUMO

[FeFe] hydrogenases demonstrate remarkable catalytic efficiency in hydrogen evolution and oxidation processes. However, susceptibility of enzymes to oxygen-induced degradation impedes their practical deployment in hydrogen-production devices and fuel cells. Recent investigations into the oxygen-stable (Hinact) state of the H-cluster revealed its inherent capacity to resist oxygen degradation. Herein, we present findings on Cl-/SH-bound [2Fe-2S] complexes, bearing relevance to the oxygen-stable state within a biological context. A characteristic attribute of these complexes is the terminal Cl-/SH- ligation to the iron bearing the CO bridge. Structural analysis of the t-Cl demonstrates a striking resemblance to the Hinact state of DdHydAB and CbA5H. The t-Cl/t-SH exhibit reversible oxidation, with both redox species, electronically, being the first biomimetic analogs to the Htrans and Hinact states. These complexes exhibit notable resistance against oxygen-induced decomposition, supporting the potential oxygen-resistant nature of the Htrans and Hinact states. The swift reductive release of the Cl-/SH- demonstrates its labile and kinetically controlled binding. The findings garnered from these investigations offer valuable insights into properties of the enzymatic O2-stable state, and key factors governing deactivation and reactivation conversion. This work contributes to advancement of bio-inspired molecular catalysts and integration of enzymes and artificial catalysts into H2-evolution devices and fuel-cell applications.

2.
J Am Chem Soc ; 146(1): 833-848, 2024 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-38113458

RESUMO

The high-performance Y6-based nonfullerene acceptors (NFAs) feature a C-shaped A-DA'D-A-type molecular architecture with a central electron-deficient thiadiazole (Tz) A' unit. In this work, we designed and synthesized a new A-D-A-type NFA, termed CB16, having a C-shaped ortho-benzodipyrrole-based skeleton of Y6 but with the Tz unit eliminated. When processed with nonhalogenated xylene without using any additives, the binary PM6:CB16 devices display a remarkable power conversion efficiency (PCE) of 18.32% with a high open-circuit voltage (Voc) of 0.92 V, surpassing the performance of the corresponding Y6-based devices. In contrast, similarly synthesized SB16, featuring an S-shaped para-benzodipyrrole-based skeleton, yields a low PCE of 0.15% due to the strong side-chain aggregation of SB16. The C-shaped A-DNBND-A skeleton in CB16 and the Y6-series NFAs constitutes the essential structural foundation for achieving exceptional device performance. The central Tz moiety or other A' units can be employed to finely adjust intermolecular interactions. The single-crystal X-ray structure reveals that ortho-benzodipyrrole-embedded A-DNBND-A plays an important role in the formation of a 3D elliptical network packing for efficient charge transport. Solution structures of the PM6:NFAs detected by small- and wide-angle X-ray scattering (SWAXS) indicate that removing the Tz unit in the C-shaped skeleton could reduce the self-packing of CB16, thereby enhancing the complexing and networking with PM6 in the spin-coating solution and the subsequent device film. Elucidating the structure-property-performance relationships of A-DA'D-A-type NFAs in this work paves the way for the future development of structurally simplified A-D-A-type NFAs.

3.
Dalton Trans ; 52(7): 1939-1949, 2023 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-36691828

RESUMO

The self-assembly of tetrarhenium metallacycles [{Re(CO)3}2(µ-dhaq)(µ-N-N)]2 (3a, N-N = 1,3-bis(1-butylbenzimidazol-2-yl)benzene; 3b, N-N = 1,3-bis(1-octylbenzimidazol-2-yl)benzene), (H2-dhaq = 1,4-dihydroxy-9,10-anthraquinone) and [{Re(CO)3}2(µ-thaq)(µ-N-N)]2 (4, N-N = 1,3-bis(1-butylbenzimidazol-2-yl)benzene), (H2-thaq = 1,2,4-trihydroxy-9,10-anthraquinone) under solvothermal conditions is described. The metallacycles 3a,b and 4 underwent aggregation-induced emission enhancement (AIEE) in THF upon the incremental addition of water. TEM images revealed that metallacycle 3a in a 60% aqueous THF solution formed rectangular aggregates with a wide size distribution, while a 90% aqueous THF solution resulted in the formation of a mixture of nanorods and amorphous aggregates due to rapid and abrupt aggregation. UV-vis and emission spectral profiles supported the formation of nanoaggregates of metallacycles 3a,b and 4 upon the gradual addition of water to a THF solution containing metallacycles. Further studies indicated that these nanoaggregates were excellent probes for the sensitive and selective detection of nitro group containing picric acid (PA) derivatives as well as antibiotics.

4.
Inorg Chem ; 62(2): 916-929, 2023 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-36584668

RESUMO

The strong tendency to stack in the solid state and rich luminescence for the Pt(II) complexes makes them potential candidates as new mechanochromic materials and sensing applications. Six mononuclear complexes [Pt(ppy)(O4NCS2)] (1), [Pt(bpy)(O4NCS2)]ClO4 (2), [Pt(ppy)(O5NCS2)] (3), [Pt(phen)(O4NCS2)]ClO4·CH3OH (5a), [Pt(phen)(O4NCS2)]ClO4 (5b), and [Pt(phen)(O5NCS2)]ClO4 (6a), one dinuclear complex [Pt2(phen)2(NaO5NCS2)2(ClO4)3]ClO4 (6b), and one one-dimensional (1-D) coordination polymer {[Pt2(bpy)2(NaO5NCS2)2(ClO4)2](ClO4)2}n (4) were synthesized by reacting [Pt(ppy)Cl]2, Pt(bpy)Cl2, and Pt(phen)Cl2 (ppy = 2-phenylpyridine, bpy = 2,2'-bipyridine, and phen = 1,10-phenanthroline) with (1-aza-15-crown-5)dithiocarbamate (O4NCS2) or (1-aza-18-crown-6)dithiocarbamate (O5NCS2), respectively, which have been isolated and structurally characterized by X-ray diffraction. Neutral complexes 1 and 3 contain no intermolecular Pt(II)···Pt(II) contact, whereas cationic complexes 2, 5a, 5b, and 6a with ClO4- as counteranions show alternative intermolecular Pt(II)···Pt(II) contacts of 3.535/4.091, 3.480/5.001, 3.527/4.571, and 3.446/4.987 Å in the solid state, respectively. Interestingly, complex 4 forms a 1-D coordination polymer through coordination between the encapsulated Na+ ions inside the azacrown ether rings of O5NCS2 and ClO4- anions with respective intra- and intermolecular Pt(II)···Pt(II) contacts of 3.402 and 3.847 Å in crystal lattices, whereas a dinuclear complex 6b was surprisingly formed and also connected by the encapsulated Na+ ions and ClO4- anions with alternative intra- and intermolecular Pt(II)···Pt(II) contacts of 3.650 and 3.677/4.4.372 Å, respectively. Upon excitation, complexes 1 and 3 showed similar vibronic luminescence at 507, 534, and 502, 532 nm, respectively, and the other complexes 2 and 4-6 showed broad luminescence with maxima at 537-567 nm. The B3LYP/LanL2DZ calculation was carried out and used to clarify their excited-state properties. In addition, the powder samples for complexes 1-4 almost showed no energy shift for the luminescence and significantly those of complexes 5-6 exhibited the mechanochromic luminescence upon grinding. It is noted that complexes 5a and 6a only showed minor red shifts (i.e., from 544 to 556 nm for complex 5a and from 551 to 565 nm for complex 6a), whereas complex 6b exhibited a remarkable red shift from 558 to 603 nm upon grinding. Besides, their luminescence reversibility was also examined toward various solvents.

5.
Nat Commun ; 13(1): 7051, 2022 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-36396646

RESUMO

The pursuit of di-coordinate boron radical has been continued for more than a half century, and their stabilization and structural characterization remains a challenge. Here we report the isolation and structural characterization of a linear di-coordinate boron radical cation, achieved by stabilizing the two reactive atomic orbitals of the central boron atom by two orthogonal π-donating and π-accepting functionalities. The electron deficient radical cation undergoes facile one-electron reduction to borylene and binds Lewis base to give heteroleptic tri-coordinate boron radical cation. The co-existence of half-filled and empty p orbitals at boron also allows the CO-regulated electron transfer to be explored. As the introduction of CO promotes the electron transfer from a tri-coordinate neutral boron radical to a boron radical cation, the removal of CO under vacuum furnishes the reverse electron transfer from borylene to yield a solution consisting of two boron radicals.

6.
Inorg Chem ; 61(41): 16325-16332, 2022 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-36198195

RESUMO

A dimeric dithiolate-bridged species, [Fe(NO)(PS2)]2 (1) containing two {FeNO}7 units, can be isolated by treating [Fe(CO)2(NO)2] with PS2H2 (PS2H2 = bis(2-dimercaptophenyl)phenylphosphine). Crystallographic studies reveal the syn-configuration of NO units and the bridging thiolates in the butterfly shape of the 2Fe2S core. Addition of PPh3 to the solution of dinuclear 1 leads to the formation of mononuclear {FeNO}7 [Fe(NO)(PS2)(PPh3)] (2) that shows electrochemical responses similar to those of 1. One-electron reduction of 1 with Cp*2Co or KC8 results in the isolation of thiolate-bridged bimetallic DNIC, [(PS2)Fe(µ-PS2)Fe(NO)2]- ([3]-), confirmed by several spectroscopies including single-crystal X-ray diffraction studies. The bimetallic DNIC [3]- is a rare example obtained from the one-electron reduction of a dinuclear Fe-NO {FeNO}7 model complex. With the assistance of redox behaviors of 2, electrochemical studies imply that the reduction of 1 leads to the formation of a mononuclear {FeNO}8 [Fe(NO)(PS2)(THF)]- intermediate, which involves disproportionation or NO- transfer to yield [3]-. Based on IR data and magnetic properties, the electronic structure of [3]- can be described as a FeII/{Fe(NO)2}9 state. Isolation of the {Fe(NO)2}9 moiety coordinated by the Fe ancillary complex lends strong support to the NO scrambling behavior in the effectiveness of the activity of flavodiiron nitric oxide reductases (FNORs).


Assuntos
Ferro , Óxido Nítrico , Cristalografia por Raios X , Compostos Ferrosos , Ferro/química , Óxido Nítrico/química , Oxirredutases/química
7.
Dalton Trans ; 51(44): 16973-16981, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36300794

RESUMO

The reaction of potassium (aza-15-crown-5)dithiocarbamate (KO4NCS2) and (Me2S)AuCl gave the dinuclear complex [Au(O4NCS2)]2, which underwent structural transformation upon heating to rearrange into the hexanuclear complex [Au(O4NCS2)]6. Under similar reaction conditions, KO4NCS2 reacted with AgNO3 or [Cu(CH3CN)4]ClO4 to give the 1-D coordination polymer [Ag(O4NCS2)]n (1) and the tetranuclear complex [Cu(O4NCS2)]4 (2), respectively. It is noted that upon heating a similar structural transformation process occurs from tetranuclear complex 2 to the octanuclear complex [Cu(O4NCS2)]8 (2'), connected by a weak Cu⋯S contact of 2.846 Å, and it has been isolated and corroborated by powder and single-crystal X-ray diffraction studies as well. Moreover, a variety of MO4NCS2 salts (M = Li+, Na+, K+ and Rb+) were used to react with AgNO3 to construct a series of coordination architectures: [LiAg(O4NCS2)2(µ-H2O)0.5]2 (3), {Na[Ag(O4NCS2)2]}n (4), {K[Ag(O4NCS2)2]}n (5) and {Rb[Ag(O4NCS2)2]}n (6). The smallest Li+ ion only coordinates with four oxygen atoms from the same azacrown ether ring and one H2O molecule, leading to a 1-D hydrogen-bonded chain with another azacrown ether ring for complex 3. The larger Na+ ion coordinates with seven oxygen atoms from two different crown ether rings, leading to a 1-D chain for complex 4. However, the largest K+ and Rb+ ions constitute a 1-D framework, except that each metal ion coordinates with eight oxygen atoms from two different crown ether rings, featuring a 1-D helical chain for complexes 5 and 6. Hence, the different sizes of alkaline metal ions exert a dramatic effect on the structural motifs of complexes 3-6. Remarkably, the dithiocarbamate moieties adopt µ2-bridging ([Au(O4NCS2)]2 and [Au(O4NCS2)]6), µ3- and µ4-bridging (1-2) and chelate forms (3-6) in the structural backbones.


Assuntos
Complexos de Coordenação , Éteres de Coroa , Complexos de Coordenação/química , Íons , Oxigênio
8.
RSC Adv ; 12(38): 24830-24838, 2022 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-36128372

RESUMO

The straightforward preparation of N-coordinated ruthenium triazolato complexes by [3 + 2] cycloaddition reactions of a ruthenium azido complex [Ru]-N3 (1, [Ru] = (η5-C5H5)(dppe)Ru, dppe = Ph2PCH2CH2PPh2) with a series of terminal phenylacetylenes is reported. The reaction products, N(2)-bound ruthenium 4-aryl-1,2,3-triazolato complexes such as [Ru]N3C2H(4-C6H4CN) (2), [Ru]N3C2H(4-C6H4CHO) (3), [Ru]N3C2H(4-C6H4F) (4), [Ru]N3C2H(Ph) (5) and [Ru]N3C2H(4-C6H4CH3) (6) were produced from 4-ethynylbenzonitrile, 4-ethynylbenzaldehyde, 1-ethynyl-4-fluorobenzene, phenylacetylene and 4-ethynyltoluene, respectively, at 80 °C or above under an atmosphere of air. To the best of our knowledge, this is the first example of the preparation of N-coordinated ruthenium aryl-substituted 1,2,3-triazolato complexes by the [3 + 2] cycloaddition of a metal-coordinated azido ligand and a terminal aryl acetylene, less electron-deficient terminal aryl alkynes. All of the compounds have been fully characterized and the structures of complexes 2, 3, 5 and 6 were confirmed by single-crystal X-ray diffraction analysis. Each compound participates in non-covalent aromatic interactions in the solid-state structure which can be favorable in the binding of DNA/biomolecular targets and has shown great potential in the development of biologically active anticancer drugs.

9.
Dalton Trans ; 51(39): 14875-14881, 2022 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-36017779

RESUMO

Molybdenum trioxide (MoO3) with a theoretical specific capacity of 1117 mA h g-1 is widely considered a promising anode material for lithium-ion batteries. However, the irreversible conversion reactions, low electrical conductivity, and detrimental volume expansion upon Li intercalation between the one-dimensional layered structures of MoO3 hinder its practical implementation. Herein, we report a facile synthetic protocol that allows surficial modification by replacing the terminal and bridging oxo groups of molybdenum oxide clusters. Successful organoimido functionalization resulted in a large cathodic shift in Mo(VI/V) reduction by 0.6 V, pronounced electronic communication between the organic moiety and the metal-oxide unit, and significant increase in electrical conductivity (80-100 Ω interfacial charge-transfer resistance). Combined with the enlarged active surface area due to the structural hindrance induced by the organic functionality, the steady specific capacity of the organoimido-modified molybdenum oxide clusters was greater than 1200 mA h g-1 at 900 mA g-1 at the end of 360 cycles, where the best value of 1653 mA h g-1 was achieved for the nitroaniline-substituted species. The steady capacity of 480 mA h g-1 was achieved in the fast charge-discharge process (3000 mA g-1) over 1400 cycles. The results indicate that the surficial modification of metal oxides with organo moieties using our facile synthetic method has broad application potential for metal oxides to be used as high-capacity electrode materials in the future.

10.
Org Lett ; 24(28): 5155-5160, 2022 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-35802069

RESUMO

An intriguing stereoselective visible-light photocatalysis of dihydroquinoxalinone derivatives has been realized via cyclization with or without the solvolysis cascade. The reactions provided the polycyclic ring structures with efficient formation of multiple bonds and with high stereoselectivity. X-ray crystallography unequivocally determined the structures of five polycyclic products.

11.
Polymers (Basel) ; 14(9)2022 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-35566904

RESUMO

We report herein on the crystal structure and magnetic studies of a three-dimensional (3D) Ni(II)-chromate coordination polymer, [Ni(CrO4)(bpym)(H2O)]n (1; bpym = 5,5'-bipyrimidin), prepared by self-assembly of Ni(II) and chromate ions with a multi-N donor auxiliary ligands, bpym, through hydrothermal processes. The structure of 1 is composed of Ni(II)-CrO4 layers with [Ni3(µ3-CrO4)] triangular motifs, in which the Ni(II) centers are bridged by O':O':O':µ3-CrO42- anions, and the resulting layers are further connected by twisted trans-µ2-N,N'-bpym auxiliary ligands to form a 3D pillar-layered network with an hms topology. The magnetic properties of compound 1 were illustrated by variable field and temperature magnetic susceptibility measurements. The findings reveal that compound 1 shows intralayer ferromagnetic interactions within Ni(II)-CrO4 layers, and furthers the 3D antiferromagnetic ordering in the resulting of interlayer antiferromagnetic couplings with a Néel temperature (TN) of 5.6 K. In addition, compound 1 shows the field-induced metamagnetic behavior at temperature below the TN.

12.
Org Lett ; 24(18): 3353-3357, 2022 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-35499378

RESUMO

First total synthesis of ulodione A has been achieved via the key-step reactions of DIPEA-promoted dialkytion of 1,3-cyclopentadione with a bromonitroolefin and DABCO promoted/catalytic semipinacol-like ring-expansion rearrangement, with regioselective transformation of the nitrocyclohexane intermediates to their cyclopentenone counterparts via a sequence of reactions in a one-pot operation. Structures of six products were unequivocally established by X-ray crystallography.


Assuntos
Piperazinas , Alquilação , Catálise , Estrutura Molecular
13.
ACS Omega ; 7(16): 14089-14101, 2022 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-35559195

RESUMO

Two ligand ratio-dependent supramolecular networks, [Cd(2,2'-bpym)1.5(BDC)]·0.5(2,2'-bpym)·5H2O (1) and [Cd(2,2'-bpym)0.5(BDC)(H2O)3] (2), (BDC2- = dianion of terephthalic acid and 2,2'-bpym = 2,2'-bipyrimidine) have been synthesized and structurally characterized by the single-crystal X-ray diffraction method. Structural determination reveals that compound 1 is a two-dimensional (2D) layered metal-organic framework (MOF) constructed via the bridges of Cd(II) ions with 2,2'-bpym and BDC2- ligands, and compound 2 is a zero-dimensional (0D) 2,2'-bpym-bridged di-Cd(II) monomeric complex. When the thermally dehydrated powders of 1 (at 100 °C) were immersed into water solution, most of the dehydrated powders of 1 underwent structural transformation back to rehydrated 1, but very little amounts of the dehydrated powders of 1 were decomposed to light-brown crystals of 2 or colorless crystals of a new coordination polymer (CP), [Cd(2,2'-bpym)(BDC)(H2O)]·3H2O (3), with its one-dimensional (1D) zigzag chain-like framework being constructed via the bridges of Cd(II) ions with the BDC2- ligand. Structural analysis reveals that all 3D supramolecular networks of 1-3 are further constructed via strong intermolecular interactions, including hydrogen bonds and π-π stacking interactions. Compounds 1 and 2 both exhibit significant water vapor hysteresis isotherms, and their cyclic water de-/adsorption behavior accompanied with solid-state structural transformation has been verified by de-/rehydration TG analyses and powder X-ray diffraction (PXRD) measurements.

14.
ACS Omega ; 6(48): 33192-33199, 2021 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-34901670

RESUMO

The bifunctional ligands of isonicotinic acid (Py-4-COOH) and 4-pyrid-4-ylbenzoic acid (Pybz-4-COOH) instead of polypyridines were therefore reacted with (Re(CO)4)3(C3N3S3) (C3N3S3 = cyanurate trianion), resulting in the formation of two trinuclear [(Re(CO)3)3(C3N3S3)(Py-4-COOH)3] (1) and [(Re(CO)3)3(C3N3S3)(Pybz-4-COOH)3] (2), respectively. In the meantime, both complexes 1 and 2 are connected by three bifurcated hydrogen bonds between their carboxylic acid moieties Py-4-COOH and Pybz-4-COOH to form the supramolecular trigonal-prismatic and -antiprismatic structures, respectively. It is noted that complex 1 can further react with copper(II) nitrate upon deprotonation to give nonanuclear [(Re(CO)3)3(C3N3S3)(Py-4-COO)3]2Cu3(H2O)9 (3), where two trinuclear [(Re(CO)3)3(C3N3S3)(Py-4-COO)3] moieties are connected by three penta-coordinate copper(II) ions, each coordinating to two carboxylates and three water molecules, to form the trigonal-prismatic structure. Surprisingly, addition of pyrazine (pz) in the synthetic process of complex 3 resulted in serendipitous isolation of a rare example of octadecanuclear {[(Re(CO)3)3(C3N3S3)(Py-4-COO)3]2Cu3(H2O)6(pz)2}2 (4), which can be regarded as a dimer of complex 3, connected by two bridging pz ligands. Interestingly, both complexes 3 and 4 are heteronuclear molecular Re(I)-Cu(II) boxes, constructed by a complex-as-a-ligand strategy. Furthermore, complexes 1 and 2 can exhibit respective low-energy luminescence at ca. 561 and 534 nm at room temperature upon photoexcitation, and complex 3 is found to display antiferromagnetic coupling of -127.68 and -134.70 cm-1, possibly due to multiple hydrogen bonds inducing significant Cu(II)···Cu(II) coupling.

15.
JACS Au ; 1(9): 1389-1398, 2021 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-34604849

RESUMO

The O-O bond length is often used as a structural indicator to determine the valence states of bound O2 ligands in biological metal-dioxygen intermediates and related biomimetic complexes. Here, we report very distinct O-O bond lengths found for three crystallographic forms (1.229(4), 1.330(4), 1.387(2) Šat 100 K) of a side-on iron-dioxygen species. Despite their different O-O bond distances, all forms possess the same electronic structure of Fe(III)-O2 •-, as evidenced by their indistinguishable spectroscopic features. Density functional theory and ab initio calculations, which successfully reproduce spectroscopic parameters, predict a flat potential energy surface of an η2-O2 motif binding to the iron center regarding the O-O distance. Therefore, the discrete O-O bond lengths observed likely arise from differential intermolecular interactions in the second coordination sphere. The work suggests that the O-O distance is not a reliable benchmark to unequivocally identify the valence state of O2 ligands for metal-dioxygen species in O2-utilizing metalloproteins and synthetic complexes.

16.
Mar Drugs ; 19(10)2021 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-34677460

RESUMO

Sponge-derived scalaranes are remarkable sesterterpenoids previously found to exhibit profound inhibitory effects against neutrophilic inflammation. In our current work, we constructed the metabolomic profile of marine sponge Lendenfeldia sp. for the first time using a tandem mass spectrometry (MS/MS) molecular networking approach. The results highlighted the rich chemical diversity of these scalaranes, motivating us to conduct further research to discover novel scalaranes targeting neutrophilic inflammation. MS- and NMR-assisted isolation and elucidation led to the discovery of seven new homoscalaranes, lendenfeldaranes K-Q (1-7), characterized by methylation at C-24, together with five known derivatives, lendenfeldarane B (8), 25-nor-24-methyl-12,24-dioxoscalar-16-en-22-oic acid (9), 24-methyl-12,24,25-trioxoscalar-16-en-22-oic acid (10), felixin B (11), and 23-hydroxy-20-methyldeoxoscalarin (12). Scalaranes 1-4 and 6-12 were assayed against superoxide anion generation and elastase release, which represented the neutrophilic inflammatory responses of respiratory burst and degranulation, respectively. The results indicated that 1-3 and 6-12 exhibited potential anti-inflammatory activities (IC50 for superoxide anion scavenging: 0.87~6.57 µM; IC50 for elastase release: 1.12~6.97 µM).


Assuntos
Anti-Inflamatórios/farmacologia , Neutrófilos/efeitos dos fármacos , Poríferos , Sesterterpenos/farmacologia , Animais , Anti-Inflamatórios/química , Organismos Aquáticos , Humanos , Inflamação/prevenção & controle , Sesterterpenos/química , Relação Estrutura-Atividade
17.
Org Lett ; 23(12): 4688-4693, 2021 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-34048266

RESUMO

The organocatalytic α-alkylation of vinylogous carbonyl compounds to hydroxynitroolefins for the synthesis of hemiacetals was realized with excellent enantioselectivities and in high yields. High diastereoselectivity (up to >20:1) has been accomplished with the addition of Et3N. The α- and γ-alkylation of vinylogous ketone against nitroolefins displayed high but opposite facial selectivities. Transformation of the hemiacetal products to other polycyclic compounds, including the euroticin B analog, has been demonstrated.

18.
Mar Drugs ; 19(3)2021 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-33673526

RESUMO

Two cembranoids, including a new compound, lobocrassin I (1), as well as a known analogue, lobohedleolide (2), were obtained by solvent extraction from octocoral Lobophytum crassum. This study employed a spectroscopic approach to establish the structures of these two cembranoids, and utilized single-crystal X-ray diffraction analysis to determine their absolute configurations. The results of biological activity assays demonstrated that cembranoid 2 exhibited bioactivity against the protein expressions of inducible nitric oxide synthase (iNOS) lipopolysaccharide (LPS)-treated RAW 264.7 mouse macrophage cells.


Assuntos
Antozoários/química , Anti-Inflamatórios/isolamento & purificação , Diterpenos/isolamento & purificação , Animais , Anti-Inflamatórios/química , Anti-Inflamatórios/farmacologia , Diterpenos/química , Diterpenos/farmacologia , Lipopolissacarídeos , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Óxido Nítrico Sintase Tipo II/genética , Células RAW 264.7 , Difração de Raios X
19.
ACS Appl Mater Interfaces ; 13(13): 15437-15447, 2021 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-33759493

RESUMO

A new class of bis-tridentate Ir(III) complexes (Dap-1-4) was synthesized using carbene pincer pro-chelates PC1·H3(PF6)2 or PC2·H3(PF6)2 with either imidazolylidene or imidazo[4,5-b]pyridin-2-ylidene appendages, together with a second cyclometalating 2,6-diaryoxypyridine chelate, L1H2 and L2H2, differed by a NMe2 donor at the central pyridinyl fragment. The respective emission tuning between the ultraviolet and blue region was rationalized using time-dependent density functional theory (TD-DFT) approaches. Next, a highly efficient blue emitter (Dap-5) was synthesized by concomitant addition of two methyl groups and a single CF3 substituent at the central phenyl and peripheral imidazo[4,5-b]pyridin-2-ylidene entities of the carbene pincer chelate, respectively. The organic light-emitting diode (OLED) device with 15 wt % Dap-5 in DPEPO shows electroluminescence at 468 nm and with CIE (0.14, 0.15) and a max external quantum efficiency (max EQE) of 16.8% with low efficiency roll-off (EQE of 14.4% at 1000 cd m-2); the latter is attributed to the relatively shortened triplet excited-state radiative lifetime. These results highlight the adequateness of bis-tridentate Ir(III) phosphors in fabrication of practical blue-emitting OLEDs.

20.
Inorg Chem ; 60(7): 4764-4771, 2021 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-33721490

RESUMO

The reaction of Re(CO)5Cl with 4-mercaptopyridine (4-PySH) led to the formation of [Re(CO)3(4-HPyS)3]Cl (1), showing three hydrogen-bonding donors of 4-PySH ligands as well as a characteristic ligand-to-metal charge-transfer absorption at ca. 380 nm. In this regard, a variety of anions, i.e., CN-, OAc-, F-, Cl-, Br-, I-, PF6-, NO3-, ClO4-, and H2PO4-, were examined to study anion-recognition studies through hydrogen-bonding functionalities. Upon the addition of CN- to a methanolic solution of complex 1, a remarkable spectral change with an isosbestic point at ca. 314 nm in the absorption spectra was observed, with a binding constant (Kb) calculated to be 24770 M-1. Moreover, the OAc- anion also shows a similar trend, but a mild spectral change, with Kb calculated to be 2170 M-1. Unlike those of CN- and OAc-, the addition of F-, Cl-, Br-, and I- anions causes a less pronounced spectral change with an isosbestic point at ca. 350 nm and Kb calculated to be 2863-750 M-1. However, almost no spectral change can be observed for other anions (i.e., PF6-, NO3-, H2PO4-, and ClO4-). Interestingly, the molecular loops of [Re(CO)3Cl(Py2S2)]2 (2; Py2S2 = 4,4'-dipyridyl disulfide) and [Re(CO)3Cl(Py2S)0.35(Py2S2)0.65]2 (3; Py2S = 4,4'-dipyridyl sulfide) can be isolated and structurally characterized by X-ray diffraction, where those crystals were grown from diethyl ether diffusion into a methanolic solution of complex 1 with [Bu4N]CN and [Bu4N]NO3, respectively. It is noted that such unusual ligand-coupling reactions toward the homoligand and hybrid-ligand loops of complexes 2 and 3 can be achieved at room temperature in this study.

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