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1.
J Am Chem Soc ; 146(25): 17348-17354, 2024 Jun 26.
Article in English | MEDLINE | ID: mdl-38864188

ABSTRACT

Our study unveils a novel approach to accessing boryl radicals through the spontaneous homolytic cleavage of B-B bonds. We synthesized a hexaaryl-substituted diboron(6) dianion, 1, via the reductive B-B coupling of 9-borafluorene. Intriguingly, compound 1 exhibits the ability to undergo homolytic B-B bond cleavage, leading to the formation of boryl radical anions, as confirmed by EPR studies, in the presence of the 2.2.2-cryptand at room temperature. Moreover, it directly reacts with diphenylacetylene, producing an unprecedented 1,6-diborylated allene species, where the phenyl ring is dearomatized. Density functional theory computational studies suggest that homolytic B-B bond cleavage is favored in the reaction path, and the formation of the boryl radical anion is crucial for dearomatization. Additionally, it achieves the dearomative diborylation of anthracene and the activation of elemental sulfur/selenium under mild conditions. The borylation products have been successfully characterized by NMR spectra, HRMS, and X-ray single-crystal diffraction.

2.
Heliyon ; 9(8): e18946, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37636375

ABSTRACT

DNA barcoding of herbs allows accurate species authentication. However, the DNA of herbs are often not easily PCR amplified due to co-extraction of inhibitors. Methods have been developed to improve DNA extraction to reduce contaminants. These methods usually require toxic chemical treatments or expensive commercial kits and are labor intensive. In this report, we collected the air passed from the herbs and directly amplified the DNA obtained. Results showed that DNA could be obtained, and it was PCR amplifiable. Sequencing of the amplified DNA allowed species authentication. This DNA collection method is applicable to herbs from different plant tissues. It has the advantages of reducing the use of toxic substances and more economical.

3.
Front Chem ; 11: 1195883, 2023.
Article in English | MEDLINE | ID: mdl-37332894

ABSTRACT

Introduction: The plant Patrinia villosa Juss. (PV) has long been used as a medicinal herb for treating intestinal disorders. Pharmacological activities such as anti-oxidation, anti-inflammation, and anti-cancer effects of compounds isolated from PV have been reported, but these bioactive compounds were not derived from PV water extract (PVW). Therefore, in the present study, we aimed to identify the active component(s) of PVW which exhibit inhibitory activities in colon cancer cells viability and migration. Methods: Human colon cancer HCT116 cells were treated with the isolated compounds of PVW and then subjected to MTT and transwell migration assays. Results: Our results showed that an active compound in PVW, 8,9-didehydro-7-hydroxydolichodial (DHD) inhibited cell viability of HCT116 cells, with IC50 value at 6.1 ± 2.2 µM. Interestingly, DHD was not detected in the herbal material of PV. Further investigation revealed that DHD is in fact a heat-generated compound derived from a natural compound present in PV, namely valerosidate. Valerosidate also reduced cell viability in HCT116 cells, with IC50 value at 22.2 ± 1.1 µM. Moreover, both DHD (2.75 µM) and valerosidate (10.81 µM) suppressed cell migration in HCT116 cells, with inhibitory rates at 74.8% and 74.6%, respectively. In addition, western blot results showed that DHD (5.5 µM) could significantly increase p53 expression by 34.8% and PTEN expression by 13.9%, while valerosidate (21.6 µM) could increase expressions of p53 and PTEN by 26.1% and 34.6%, respectively in HCT116 cells after 48 h treatment. Discussion: Taken together, this is the first report that a naturally-occurring valerosidate present in PV could actually transform to DHD by thermal hydrolysis, and both compounds exhibited inhibitory effects on cell viability and migration in HCT116 cells via increasing the expressions of tumor suppressors (p53 and PTEN). Our findings demonstrated that valerosidate is present in raw herb PV but not in PVW, while DHD is present in PVW rather than in raw herb PV. This difference in chemical profiles of raw herb and boiled water extract of PV may affect the anti-cancer activity, and hence further investigations are warranted.

4.
J Ethnopharmacol ; 309: 116322, 2023 Jun 12.
Article in English | MEDLINE | ID: mdl-36868436

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: Ilex pubescens Hook. et Arn. (Maodongqing, MDQ) is a common herbal tea ingredient in Southern China for heat clearance and anti-inflammation. Our preliminary screening showed that 50% ethanol extract of its leaves has anti-influenza virus activity. In this report, we proceed to identify the active components and clarify the related anti-influenza mechanisms. AIM: We aim to isolate and identify the anti-influenza virus phytochemicals from the extract of the MDQ leaves, and study their anti-influenza virus mechanism. MATERIAL AND METHODS: Plaque reduction assay was used to test the anti-influenza virus activity of fractions and compounds. Neuraminidase inhibitory assay was used to confirm the target protein. Molecular docking and reverse genetics were used to confirm the acting site of caffeoylquinic acids (CQAs) on viral neuraminidase. RESULTS: Eight CQAs, 3,5-di-O-caffeoylquinic acid methyl ester (Me 3,5-DCQA), 3,4-di-O-caffeoylquinic acid methyl ester (Me 3,4-DCQA), 3,4,5-tri-O-caffeoylquinic acid methyl ester (Me 3,4,5-TCQA), 3,4,5-tri-O-caffeoylquinic acid (3,4,5-TCQA), 4,5-di-O-caffeoylquinic acid (4,5-DCQA), 3,5-di-O-caffeoylquinic acid (3,5-DCQA), 3,4-di-O-caffeoylquinic acid (3,4-DCQA), and 3,5-di-O-caffeoyl-epi-quinic acid (3,5-epi-DCQA) were identified from the MDQ leaves, in which Me 3,5-DCQA, 3,4,5-TCQA and 3,5-epi-DCQA were isolated for the first time. All these eight compounds were found to inhibit neuraminidase (NA) of influenza A virus. The results of molecular docking and reverse genetics indicated that 3,4,5-TCQA interacted with Tyr100, Gln412 and Arg419 of influenza NA, and a novel NA binding groove was found. CONCLUSION: Eight CQAs isolated from the leaves of MDQ were found to inhibit influenza A virus. 3,4,5-TCQA was found to interact with Tyr100, Gln412 and Arg419 of influenza NA. This study provided scientific evidence on the use of MDQ for treating influenza virus infection, and laid the foundation for the development of CQA derivatives as potential antiviral agents.


Subject(s)
Ilex , Quinic Acid , Quinic Acid/pharmacology , Quinic Acid/chemistry , Molecular Docking Simulation , Neuraminidase , Plant Extracts/pharmacology , Plant Extracts/chemistry , Biological Assay
5.
ACS Chem Neurosci ; 14(2): 289-299, 2023 01 18.
Article in English | MEDLINE | ID: mdl-36580663

ABSTRACT

Expansions of ATTTT and ATTTC pentanucleotide repeats in the human genome are recently found to be associated with at least seven neurodegenerative diseases, including spinocerebellar ataxia type 37 (SCA37) and familial adult myoclonic epilepsy (FAME) types 1, 2, 3, 4, 6, and 7. The formation of non-B DNA structures during some biological processes is thought as a causative factor for repeat expansions. Yet, the structural basis for these pyrimidine-rich ATTTT and ATTTC repeat expansions remains elusive. In this study, we investigated the solution structures of ATTTT and ATTTC repeats using nuclear magnetic resonance spectroscopy. Here, we reveal that ATTTT and ATTTC repeats can form a highly compact minidumbbell structure at the 5'-end using their first two repeats. The high-resolution structure of two ATTTT repeats was determined, showing a regular TTTTA pentaloop and a quasi TTTT/A pentaloop. Furthermore, the minidumbbell structure could escape from proofreading by the Klenow fragment of DNA polymerase I when it was located at five or more base pairs away from the priming site, leading to a small-scale repeat expansion. Results of this work improve our understanding of ATTTT and ATTTC repeat expansions in SCA37 and FAMEs, and provide high-resolution structural information for rational drug design.


Subject(s)
Epilepsies, Myoclonic , Nerve Tissue Proteins , Spinocerebellar Ataxias , Adult , Humans , Magnetic Resonance Imaging , Magnetic Resonance Spectroscopy , Microsatellite Repeats , Nerve Tissue Proteins/genetics , Spinocerebellar Ataxias/genetics , Epilepsies, Myoclonic/genetics
6.
J Am Chem Soc ; 144(36): 16612-16619, 2022 Sep 14.
Article in English | MEDLINE | ID: mdl-36043840

ABSTRACT

Herein, we report robust π-conjugated radical cations resulting from the oxidation of hexabenzoperylene (HBP) derivatives, HBP-B and HBP-H, which have butyl and hexyl groups, respectively, attached to the same twisted double helicene π-backbone. The radical cation of HBP-B was successfully crystallized in the form of hexafluorophosphate, which exhibited conductivity as high as 1.32 ± 0.04 S cm-1. Photochemical oxidation of HBP-H by molecular oxygen led to the formation of its radical cation in the solid state, as found with different techniques. This allowed the organic field effect transistor of HBP-H to function as a nonvolatile optoelectronic memory, with the memory switching contrast above 103 and long-term stability without using a floating gate, an electret layer, or photochromic molecules.

7.
J Am Chem Soc ; 144(17): 7588-7593, 2022 05 04.
Article in English | MEDLINE | ID: mdl-35442033

ABSTRACT

As a strategy to design stable but highly reactive metal nitrido species, we have synthesized a manganese(V) nitrido complex bearing a bulky corrole ligand, [MnV(N)(TTPPC)]- (1, TTPPC is the trianion of 5,10,15-Tris(2,4,6-triphenylphenyl)corrole). Complex 1 is readily oxidized by 1 equiv of Cp2Fe+ to give the neutral complex 2, which can be further oxidized by 1 equiv of [(p-Br-C6H4)3N•+][B(C6F5)4] to afford the cationic complex 3. All three complexes are stable in the solid state and in CH2Cl2 solution, and their molecular structures have been determined by X-ray crystallography. Spectroscopic and theoretical studies indicate that complexes 2 and 3 are best formulated as Mn(V) nitrido π-cation corrole [MnV(N)(TTPPC+•)] and Mn(V) nitrido π-dication corrole [MnV(N)(TTPPC2+)]+, respectively. Complex 3 is the most reactive N atom transfer reagent among isolated nitrido complexes; it reacts with PPh3 and styrene with second-order rate constants of 2.12 × 105 and 1.95 × 10-2 M-1 s-1, respectively, which are >107 faster than that of 2.


Subject(s)
Manganese , Porphyrins , Electrons , Ions , Ligands , Manganese/chemistry , Porphyrins/chemistry
8.
PLoS One ; 17(4): e0267143, 2022.
Article in English | MEDLINE | ID: mdl-35421189

ABSTRACT

We set forth to assess the quality of an herbal medicine sold in Hong Kong called Qianliguang by employing a multi-methodological approach. The quality is set by its identity, chemical composition, and bioactivities, among others. Qianliguang (Senecionis scandentis Herba, Senecio scandens Buch.-Ham. ex D.Don) has known antibacterial properties. However, it is poisonous and overconsumption can result in liver damage. Eighteen Qianliguang samples were purchased from herbal shops at various districts in Hong Kong. Samples were first authenticated organoleptically. DNA barcoding at the psbA-trnH, ITS2, and rbcL loci was then conducted to confirm the species. HPLC-UV was performed to screen for the presence of the chemical compounds and to quantify the flavonoid hyperoside. UPLC-MS was used to quantify the amount of the toxic pyrrolizidine alkaloid (PA) adonifoline. Microdilution assay was performed to show the antibacterial effect on Streptococcus aureus and S. pneumoniae. Results showed that five samples were found to be substituted by species belonging to the genus Lespedeza; four samples were mixtures containing not only Qianliguang but also Achyranthes aspera L., Lonicera confusa DC., or Solanum nigrum L. HPLC-UV showed that only ten contained enough hyperoside to meet the standard requirement. In addition, nine samples had adonifoline that exceeded the toxicity standard requirement. In the microdilution assay, samples containing Qianliguang showed inhibition on S. aureus and S. pneumoniae, while among the five Lespedeza sp. samples the antibacterial effects on S. aureus were not detectable; only one sample showed inhibition to S. pneumoniae. Our study illustrated the necessity of using a multi-methodological approach for herbal medicine quality assessment. We also showed that Qianliguang samples in the Hong Kong market were either toxic or adulterated. It is therefore essential to improve the quality control of Qianliguang and probably other herbs in the herbal market.


Subject(s)
Plants, Medicinal , Senecio , Anti-Bacterial Agents/pharmacology , Chromatography, Liquid , DNA Barcoding, Taxonomic , Plants, Medicinal/genetics , Senecio/genetics , Staphylococcus aureus/genetics , Tandem Mass Spectrometry
9.
J Ethnopharmacol ; 292: 115175, 2022 Jun 28.
Article in English | MEDLINE | ID: mdl-35306041

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: Canarium album (Lour.) DC. belongs to the Burseraceae family. Its leaf, named as Ganlanye (GLY), was recorded to treat warm disease symptoms via clearing lung heat and toxicants in medical classics. Its aqueous extract had anti-influenza activity in our previous phenotypic screening. However, its active components and mechanism were not identified. AIM: We aim to isolate the anti-influenza phytochemicals from GLY extract and explore its anti-flu mechanism. MATERIAL AND METHODS: Influenza A virus infected MDCK cells were used to test the compounds and fractions. Structural analyses of new compounds were performed via NMR calculation with the combination of DP4plus probability method and computed electronic circular dichroism (ECD). Hemagglutination inhibitory assay and neuraminidase inhibitory assay were performed to find the target protein. Molecular docking and recombinant virus were used to confirm the action site of the three new canaroleosides. RESULTS: Three new phenolic glycosides, canaroleosides A-C (1-3), and three known flavonoids (4-6), were isolated from the GLY aqueous extract and their anti-influenza virus mechanism was revealed. The absolute configurations of 1-3 were determined by ECD method, with the structure of the 2,5-dihydroxybenzoic acid moiety in 1 assigned by NMR calculation. Compound 1 was found to suppress both hemagglutinin and neuraminidase activities. Compounds 2, 3 4 and 6 inhibited neuraminidase, while compound 5 inhibited hemagglutinin. 1-3 could interact with Arg152 of the viral neuraminidase based on the result of molecular docking and reverse genetics. CONCLUSION: Six phytochemicals were isolated from GLY aqueous extract and found to inhibit influenza A strains. They were found to interact with hemagglutinin or neuraminidase and canaroleosides 1-3 could interact with Arg152 of the viral neuraminidase. This study provided more evidence on the anti-influenza effect of Ganlan and laid the foundation for further generation of potent NA inhibitors.


Subject(s)
Burseraceae , Influenza, Human , Antiviral Agents , Burseraceae/chemistry , Hemagglutinins , Humans , Molecular Docking Simulation , Neuraminidase , Phytochemicals/pharmacology , Plant Extracts/pharmacology
10.
FEBS Lett ; 596(6): 826-840, 2022 03.
Article in English | MEDLINE | ID: mdl-35060128

ABSTRACT

Minidumbbell (MDB) is a noncanonical DNA structure found to form in several pyrimidine-rich short tandem repeats associated with neurodegenerative diseases. The most recently reported MDB contains two pentaloops formed by ATTCT repeats. Here, we studied the effects of a purine residue and a backbone discontinuous site on the structure and thermal stability of MDBs containing two pentaloops. It was found that a purine as the fourth loop residue improved the thermal stability of MDBs containing two regular pentaloops, while a backbone discontinuous site between the third and fourth, or between the fourth and fifth loop residues enhanced the thermal stability of MDBs containing a regular and a quasi pentaloops. The results of this study provide new insights into the sequence criteria and structural basis of MDBs.


Subject(s)
DNA , Purines , DNA/chemistry , DNA/genetics , Nucleic Acid Conformation
11.
J Am Chem Soc ; 143(38): 15863-15872, 2021 09 29.
Article in English | MEDLINE | ID: mdl-34498856

ABSTRACT

Manganese complexes in +6 oxidation state are rare. Although a number of Mn(VI) nitrido complexes have been generated in solution via one-electron oxidation of the corresponding Mn(V) nitrido species, they are too unstable to isolate. Herein we report the isolation and the X-ray structure of a Mn(VI) nitrido complex, [MnVI(N)(TAML)]- (2), which was obtained by one-electron oxidation of [MnV(N)(TAML)]2- (1). 2 undergoes N atom transfer to PPh3 and styrenes to give Ph3P═NH and aziridines, respectively. A Hammett study for various p-substituted styrenes gives a V-shaped plot; this is rationalized by the ability of 2 to function as either an electrophile or a nucleophile. 2 also undergoes hydride transfer reactions with NADH analogues, such as 10-methyl-9,10-dihydroacridine (AcrH2) and 1-benzyl-1,4-dihydronicotinamide (BNAH). A kinetic isotope effect of 7.3 was obtained when kinetic studies were carried out with AcrH2 and AcrD2. The reaction of 2 with NADH analogues results in the formation of [MnV(N)(TAML-H+)]- (3), which was characterized by ESI/MS, IR spectroscopy, and X-ray crystallography. These results indicate that this reaction occurs via an initial "separated CPET" (separated concerted proton-electron transfer) mechanism; that is, there is a concerted transfer of 1 e- + 1 H+ from AcrH2 (or BNAH) to 2, in which the electron is transferred to the MnVI center, while the proton is transferred to a carbonyl oxygen of TAML rather than to the nitrido ligand.

12.
Int J Mol Sci ; 22(7)2021 Mar 31.
Article in English | MEDLINE | ID: mdl-33807305

ABSTRACT

DNA methylation is a prevalent regulatory modification in prokaryotes and eukaryotes. N1-methyladenine (m1A) and N6-methyladenine (m6A) have been found to be capable of altering DNA structures via disturbing Watson-Crick base pairing. However, little has been known about their influences on non-B DNA structures, which are associated with genetic instabilities. In this work, we investigated the effects of m1A and m6A on both the structure and thermodynamic stability of a newly reported DNA minidumbbell formed by two TTTA tetranucleotide repeats. As revealed by the results of nuclear magnetic resonance spectroscopic studies, both m1A and m6A favored the formation of a T·m1A and T·m6A Hoogsteen base pair, respectively. More intriguingly, the m1A and m6A modifications brought about stabilization and destabilization effects on the DNA minidumbbell, respectively. This work provides new biophysical insights into the effects of adenine methylation on the structure and thermodynamic stability of DNA.


Subject(s)
Adenine/chemistry , DNA Methylation/genetics , DNA/chemistry , Base Pairing/genetics , DNA Methylation/physiology , Hydrogen Bonding , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular/methods , Nucleic Acid Conformation , Nucleotide Motifs/genetics , Thermodynamics
13.
J Am Chem Soc ; 143(13): 5231-5238, 2021 Apr 07.
Article in English | MEDLINE | ID: mdl-33764047

ABSTRACT

This study explores a bottom-up approach toward negatively curved carbon allotropes from octabenzo[8]circulene, a negatively curved nanographene. Stepwise chemical reduction reactions of octabenzo[8]circulene with alkali metals lead to a unique highly reduced hydrocarbon pentaanion, which is revealed by X-ray crystallography suggesting a local view for the reduction and alkali metal intercalation processes of negatively curved carbon allotropes. Polymerization of the tetrabromo derivative of octabenzo[8]circulene by the nickel-mediated Yamamoto coupling reaction results in a new type of porous carbon-rich material, which consists of a covalent network of negatively curved nanographenes. It has a specific surface area of 732 m2 g-1 and functions as anode material for lithium ion batteries exhibiting a maximum capacity of 830 mAh·g-1 at a current density of 100 mA·g-1. These results indicate that this covalent network presents the key structural and functional features of negatively curved carbon allotropes.

14.
Chemistry ; 27(22): 6740-6747, 2021 Apr 16.
Article in English | MEDLINE | ID: mdl-33501691

ABSTRACT

Minidumbbell (MDB) is a recently identified non-B DNA structure that has been proposed to associate with genetic instabilities. It also serves as a functional structural motif in DNA nanotechnology. DNA molecular switches constructed using MDBs show instant and complete structural conversions with easy manipulations. The availability of stable MDBs can broaden their applications. In this work, we found that substitutions of cytosine with 5-methylcytosine could lead to a significant enhancement in the thermal stabilities of MDBs. Consecutive methylations of cytosine in MDBs brought about cumulative stabilization with a drastic increase in the melting temperature by 23 °C. NMR solution structures of two MDBs containing 5-methylcytosine residues have been successfully determined and revealed that the enhanced stabilities resulted primarily from favorable hydrophobic contacts, more stable base pairs and enhanced base-base stackings involving the methyl group of 5-methylcytosine.


Subject(s)
5-Methylcytosine , DNA , Base Pairing , Cytosine , Nucleic Acid Conformation , Thermodynamics
15.
Chem Commun (Camb) ; 56(70): 10127-10130, 2020 Sep 01.
Article in English | MEDLINE | ID: mdl-32870195

ABSTRACT

Here we report that incorporation of an abasic site to DNA minidumbbells formed by natural sequences can lead to significant enhancements in their thermodynamic stability. Based on these stable minidumbbells, the first metal ion-controlled molecular switch which can regulate instant and reversible DNA duplex formation and dissociation has been constructed.


Subject(s)
DNA/chemistry , Edetic Acid/chemistry , Edetic Acid/pharmacology , Magnesium/chemistry , Nucleic Acid Conformation/drug effects , Thermodynamics
16.
J Phys Chem B ; 124(25): 5131-5138, 2020 06 25.
Article in English | MEDLINE | ID: mdl-32484672

ABSTRACT

Minidumbbell (MDB) is a newly discovered DNA structure formed by native sequences, which serves as a possible structural intermediate causing repeat expansion mutations in the genome and also a functional structural motif in constructing DNA-based molecular switches. Until now, all the reported MDBs containing two adjacent type II tetraloops were formed by pyrimidine-rich sequences 5'-YYYR YYYR-3' (Y and R represent pyrimidine and purine, respectively), wherein the second and sixth residues folded into the minor groove and interacted with each other. In this study, we have conducted a high-resolution nuclear magnetic resonance (NMR) spectroscopic investigation on alternative MDB-forming sequences and discovered that an MDB could also be formed stably with a purine in the minor groove, which has never been observed in any previously reported DNA type II tetraloops. Our refined NMR solution structures of the two MDBs formed by 5'-CTTG CATG-3' and 5'-CTTG CGTG-3' reveal that the sixth purine residue was driven into the minor groove via base-base stacking with the second thymine residue and adenine stacked better than guanine. The results of our present research work expand the sequence criteria for the formation of MDBs and shed light to explore the significance of MDBs.


Subject(s)
DNA , Purines , Base Sequence , Nucleic Acid Conformation , Thymine
17.
Chemistry ; 25(56): 12895-12899, 2019 Oct 08.
Article in English | MEDLINE | ID: mdl-31325369

ABSTRACT

The synthesis and X-ray structure of a new manganese(V) mesitylimido complex with a tetraamido macrocyclic ligand (TAML), [MnV (TAML)(N-Mes)]- (1), are reported. Compound 1 is oxidized by [(p-BrC6 H4 )3 N]+. [SbCl6 ]- and the resulting MnVI species readily undergoes H-atom transfer and nitrene transfer reactions.

18.
Org Lett ; 21(3): 700-704, 2019 02 01.
Article in English | MEDLINE | ID: mdl-30675791

ABSTRACT

A new strategy was developed for the efficient synthesis of di-, tetra-, and hexa-substituted 1,3-butadienes. This one-pot procedure involves lithium-iodine exchange to generate the corresponding vinyllithium intermediates. A subsequent iron-catalyzed ligand-free oxidative homo-coupling eventually led to the formation of 1,3-butadienes in acceptable to excellent isolated yields.

19.
Chem Sci ; 10(43): 10122-10128, 2019 Nov 21.
Article in English | MEDLINE | ID: mdl-32055367

ABSTRACT

We report herein that copper alkynyl nanoclusters show metal-core dependent properties via a charge-transfer mechanism, which enables new understanding of their structure-property relationship. Initially, nanoclusters 1 and 2 bearing respective Cu(i)15 (C1) and Cu(i)28 (C2) cores were prepared and revealed to display near-infrared (NIR) photoluminescence mainly from the mixed alkynyl → Cu(i) ligand-to-metal charge transfer (LMCT) and cluster-centered transition, and they further exhibit thermally activated delayed fluorescence (TADF). Subsequently, a vanadate-induced oxidative approach to in situ generate a nucleating Cu(ii) cation led to assembly of 3 and 4 featuring respective [Cu(ii)O6]@Cu(i)47 (C3) and {[Cu(ii)O4]·[VO4]2}@Cu(i)46 (C4) cores. While interstitial occupancy of Cu(ii) triggers inter-valence charge-transfer (IVCT) from Cu(i) to Cu(ii) to quench the photoluminescence of 3 and 4, such a process facilitates charge mobility to render them semiconductive. Overall, metal-core modification results in an interplay between charge-transfer processes to switch TADF to semiconductivity, which underpins an unusual structure-property correlation for designed synthesis of metal nanoclusters with unique properties and functions.

20.
Inorg Chem ; 57(15): 9215-9222, 2018 Aug 06.
Article in English | MEDLINE | ID: mdl-29992815

ABSTRACT

Dinuclear iron nitrido phthalocyanine complexes are of interest owing to their applications in catalytic oxidation of hydrocarbons. While nitrido-bridged diiron phthalocyanine complexes are well documented, the oxidation chemistry of heterodinuclear iron(IV) phthalocyanine nitrides has not been well explored. In this paper we report on the synthesis of a heterometallic FeIV/RuIV phthalocyanine nitride and its oxidation to yield phthalocyanine cation radical and hydroxyphthalocyanine complexes. Treatment of [FeII(Pc)] (Pc2- = phthalocyanine dianion) with [RuVI(LOEt)(N)Cl2] (LOEt- = [Co(η5-C5H5){P(O)(OEt)2}3]-) (1) afforded the heterometallic µ-nitrido complex [Cl2(LOEt)RuIV(µ-N)FeIV(Pc)(H2O)] (2) that contains an RuIV=N = FeIV linkage with the Ru-N and Fe-N distances of 1.689(6) and 1.677(6) Å, respectively, and Ru-N-Fe angle of 176.0(4)°. Substitution of 2 with 4- tert-butylpyridine (Bupy) gave [Cl2(LOEt)RuIV(µ-N)FeIV(Pc)(Bupy)]. The cyclic voltammogram of 2 displayed a reversible Pc-centered oxidation couple at +0.18 V versus Fc+/0 (Fc = ferrocene). The oxidation of 2 with [N(4-BrC6H4)3]SbCl6 led to isolation of the cationic complex [Cl2(LOEt)RuIV(µ-N)FeIV(Pc·+)(H2O)][SbCl6]0.85[SbCl5(OH)]0.15 (2[SbCl6]0.85[SbCl5(OH)]0.15), whereas that with PhICl2 yielded the chloride complex [Cl2(LOEt)RuIV(µ-N)FeIV(Pc·+)Cl] (3). Complexes 2[SbCl6]0.85[SbCl5(OH)]0.15 and 3 have been characterized by X-ray crystallography. The UV/visible spectra of 2+ (λmax = 515 and 747 nm) and 3 (λmax = 506 and 748 nm) displayed absorption bands that are characteristic of Pc cation radical. The EPR spectrum of 3 showed a signal with the g value of 2.0012 (width = 5 G) that is consistent with an organic radical. The spectroscopic data support the formulation of 2+ and 3 as RuIV-FeIV Pc cation radical complexes. The reaction of 2 with PhI(CF3CO2)2 in dried CH2Cl2 afforded a mixture of [Cl2(LOEt)RuIV(µ-N)FeIV(Pc·+)(CF3CO2)] (4) and a hydroxyphthalocyanine complex, [Cl2(LOEt)RuIV(µ-N)FeIV(Pc-OH)(H2O)](CF3CO2) (5), whereas that in wet CH2Cl2 (containing ca. 0.5% water) led to isolation of 5 as the sole product. Complex 4 was independently prepared by salt metathesis of 3 with AgCF3CO2.

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