Odd-numbered and high-nuclearity coordination clusters are extremely rare,yet they represent an intriguing subclass lacking regular repeating building blocks and high structural symmetry for understanding self-assembl...Odd-numbered and high-nuclearity coordination clusters are extremely rare,yet they represent an intriguing subclass lacking regular repeating building blocks and high structural symmetry for understanding self-assembled multiatomic systems.Herein,the largest cobalt and polydentate ligand based cluster featuring odd-nuclearity,namely[Co_(19)(HL1)_(8)(L1)_(12)(L′)_(2)(Ac)_(4)]·10CH_(3)CH_(2)OH·6H_(2)O(1,H_(2)L1=1H-benzo[d]imidazole-2-yl)methanol,HL'=1H-benzo[d]imidazole),was obtained with in-situ ligand transformation from H_(2)L1 to L′.It features a hierarchical trilayer and void-cage inside structure,consisting of central disc-shaped[Co_(7)L_(10)]core with two[Co_(6)]rings on both sides.ESI-MS of crystal 1 yields a series of more than sixteen fragments,all featuring an integrated[Co_(19)]core,suggesting stability of the polynuclear cluster in solution.During increased in-source energy from 0 to 100 eV,all MS peaks shifted to a lower m/z range,but the[Co_(19)]core remained intact,excepting for the stepwise elimination of up to three Ac^(−)anions or three L1 linkers.PXRD tracking of the reaction sediments showed the formation of a key precursor of[Co_(4)L_(4)]cubane at 3 h,and its content decreased at 6 h and vanished at 12 h,followed by the appearance of crystals 1 by the generation of a clear solution at 18 h,suggesting an initial cluster assembly-disassembly process.ESI-MS spectra analysis of both reaction sediment and solution further identify the existence of other crucial higher-nuclearity reassembled fragments of[Co_(7)L_(10)]disk and its expansion of[Co_(13)L_(12)(L′)_(2)].A probable tandem assembly-disassembly-reassembly mechanism is put forward as[CoL_(2)]→[Co_(4)L_(4)]→[Co_(7)L_(10)]→[Co_(13)L_(12)(L′)_(2)]→[Co_(19)L_(2)0(L′)_(2)].Their evolution also indicated the ingenious synergy of coexisting organic,inorganic and in-situ generated ligands,along with diverse coordination geometries of metal ions,plays a directional role in forming odd-numbered and high-nuclearity coordination clusters.Magnetism analysis revealed antiferromagnetic coupling plays dominated role in the cluster.展开更多
In mass spectrometry, fragments with a mass higher than the original molecular ion provide valuable insights into the molecular structure and can guide the assembly and disassembly processes for chemical synthesis. He...In mass spectrometry, fragments with a mass higher than the original molecular ion provide valuable insights into the molecular structure and can guide the assembly and disassembly processes for chemical synthesis. Here, we report such an example and following up by modifying the solvothermal reaction conditions (temperature and time) it is possible to isolate the high mass species in crystalline form. [Zn_(4)L_(4)Cl_(4)] (Zn_(4)L_(4), L = N-methylbenzimidazole-2-methanolate) has a boat-like Zn_(4)O_(4) core but electrospray ionization mass spectrometry (ESI-MS) of the solution of its crystals shows higher mass peaks of Zn_(5)L_(5), Zn_(5)L_(6) and Zn_(6)L_(6) species. Thus, both disassembly and reassembly are highly probable processes. Consequently, [Zn(HL)_(2)Cl_(2)] (Zn1, L = N-methylbenzimidazole-2-methanolate), [Zn_(4)L_(6)Cl_(2)] (Zn_(4)L_(6), L = N-methylbenzimidazole-2-methanolate) and [Zn_(6)L_(6)Cl_(4)(CH_(3)O)_(2)] (Zn_(6)L_(6), L = N-methylbenzimidazole-2-methanolate) were prepared. The results of multistage ESI-MS of their dissolved crystals led to a proposed mechanism of their formation in the gas phase as follows: [Zn_(3)L_(4)] through [ZnL] → [ZnL(HL)] → [Zn(HL)_(2)] → [Zn_(2)L] → [Zn_(2)L_(2)] → [Zn_(2)L_(3)]. The mechanism was derived in conjunction with Gibbs free energies calculated using DFT of the fragments observed in the ESI-MS of Zn_(4)L_(4), Zn_(4)L_(6) and Zn_(6)L_(6). This work reveals the complex of chemical reactions, involving fragmentation and unexpected combination, under mass spectrometry condition which allows one to synthesize the observed transients, leading to mechanism of formation by correlation of solid-state/solution structural information.展开更多
This work aims to elucidate the chemical constituents of Kai-Xin-San（KXS） and its metabolites in rat plasma.KXS extracts were separated on an Agilent HPLC SB-C 18 column,analyzed by ion-trap tandem mass spectrometry...This work aims to elucidate the chemical constituents of Kai-Xin-San（KXS） and its metabolites in rat plasma.KXS extracts were separated on an Agilent HPLC SB-C 18 column,analyzed by ion-trap tandem mass spectrometry and high-accuracy qTOF mass spectrometry in negative ion mode.A total of 39 compounds,including 11 ginsenosides,14 Polygala saponins,5 sucrose esters,8 oligosaccharide esters and 1 xanthone were characterized from KXS.Fifteen of them were confirmed by reference standards.No constituents were detected from Poria or Acori Tatarinowii Rhizoma.After oral administration of KXS（7 g/kg）,10 ginsenosides and 18 Polygala compounds were detected in rat plasma.This study indicates that ginseng saponins,Polygala saponins and saccharide esters could be the major effective components of KXS prescription.展开更多
基金supported by the BAGUI Talent Program in Guangxi Province(No.2019AC26001)the National Natural Science Foundation of China(Nos.22171075,U23A2080,22371173).
文摘Odd-numbered and high-nuclearity coordination clusters are extremely rare,yet they represent an intriguing subclass lacking regular repeating building blocks and high structural symmetry for understanding self-assembled multiatomic systems.Herein,the largest cobalt and polydentate ligand based cluster featuring odd-nuclearity,namely[Co_(19)(HL1)_(8)(L1)_(12)(L′)_(2)(Ac)_(4)]·10CH_(3)CH_(2)OH·6H_(2)O(1,H_(2)L1=1H-benzo[d]imidazole-2-yl)methanol,HL'=1H-benzo[d]imidazole),was obtained with in-situ ligand transformation from H_(2)L1 to L′.It features a hierarchical trilayer and void-cage inside structure,consisting of central disc-shaped[Co_(7)L_(10)]core with two[Co_(6)]rings on both sides.ESI-MS of crystal 1 yields a series of more than sixteen fragments,all featuring an integrated[Co_(19)]core,suggesting stability of the polynuclear cluster in solution.During increased in-source energy from 0 to 100 eV,all MS peaks shifted to a lower m/z range,but the[Co_(19)]core remained intact,excepting for the stepwise elimination of up to three Ac^(−)anions or three L1 linkers.PXRD tracking of the reaction sediments showed the formation of a key precursor of[Co_(4)L_(4)]cubane at 3 h,and its content decreased at 6 h and vanished at 12 h,followed by the appearance of crystals 1 by the generation of a clear solution at 18 h,suggesting an initial cluster assembly-disassembly process.ESI-MS spectra analysis of both reaction sediment and solution further identify the existence of other crucial higher-nuclearity reassembled fragments of[Co_(7)L_(10)]disk and its expansion of[Co_(13)L_(12)(L′)_(2)].A probable tandem assembly-disassembly-reassembly mechanism is put forward as[CoL_(2)]→[Co_(4)L_(4)]→[Co_(7)L_(10)]→[Co_(13)L_(12)(L′)_(2)]→[Co_(19)L_(2)0(L′)_(2)].Their evolution also indicated the ingenious synergy of coexisting organic,inorganic and in-situ generated ligands,along with diverse coordination geometries of metal ions,plays a directional role in forming odd-numbered and high-nuclearity coordination clusters.Magnetism analysis revealed antiferromagnetic coupling plays dominated role in the cluster.
基金supported by the BAGUI Talent Program in Guangxi Province(No.2019AC26001),and the National Natural Science Foundation of China(No.22171075,U23A2080).
文摘In mass spectrometry, fragments with a mass higher than the original molecular ion provide valuable insights into the molecular structure and can guide the assembly and disassembly processes for chemical synthesis. Here, we report such an example and following up by modifying the solvothermal reaction conditions (temperature and time) it is possible to isolate the high mass species in crystalline form. [Zn_(4)L_(4)Cl_(4)] (Zn_(4)L_(4), L = N-methylbenzimidazole-2-methanolate) has a boat-like Zn_(4)O_(4) core but electrospray ionization mass spectrometry (ESI-MS) of the solution of its crystals shows higher mass peaks of Zn_(5)L_(5), Zn_(5)L_(6) and Zn_(6)L_(6) species. Thus, both disassembly and reassembly are highly probable processes. Consequently, [Zn(HL)_(2)Cl_(2)] (Zn1, L = N-methylbenzimidazole-2-methanolate), [Zn_(4)L_(6)Cl_(2)] (Zn_(4)L_(6), L = N-methylbenzimidazole-2-methanolate) and [Zn_(6)L_(6)Cl_(4)(CH_(3)O)_(2)] (Zn_(6)L_(6), L = N-methylbenzimidazole-2-methanolate) were prepared. The results of multistage ESI-MS of their dissolved crystals led to a proposed mechanism of their formation in the gas phase as follows: [Zn_(3)L_(4)] through [ZnL] → [ZnL(HL)] → [Zn(HL)_(2)] → [Zn_(2)L] → [Zn_(2)L_(2)] → [Zn_(2)L_(3)]. The mechanism was derived in conjunction with Gibbs free energies calculated using DFT of the fragments observed in the ESI-MS of Zn_(4)L_(4), Zn_(4)L_(6) and Zn_(6)L_(6). This work reveals the complex of chemical reactions, involving fragmentation and unexpected combination, under mass spectrometry condition which allows one to synthesize the observed transients, leading to mechanism of formation by correlation of solid-state/solution structural information.
基金National Science & Technology Mega Project forPrimary Drug Innovation from Ministry of Science and Technologyof China (Grant No. 2009ZX09502-006)
文摘This work aims to elucidate the chemical constituents of Kai-Xin-San（KXS） and its metabolites in rat plasma.KXS extracts were separated on an Agilent HPLC SB-C 18 column,analyzed by ion-trap tandem mass spectrometry and high-accuracy qTOF mass spectrometry in negative ion mode.A total of 39 compounds,including 11 ginsenosides,14 Polygala saponins,5 sucrose esters,8 oligosaccharide esters and 1 xanthone were characterized from KXS.Fifteen of them were confirmed by reference standards.No constituents were detected from Poria or Acori Tatarinowii Rhizoma.After oral administration of KXS（7 g/kg）,10 ginsenosides and 18 Polygala compounds were detected in rat plasma.This study indicates that ginseng saponins,Polygala saponins and saccharide esters could be the major effective components of KXS prescription.
