Spectroscopic Evidence for Argentophilicity in Structurally Characterized Luminescent Binuclear Silver(I) Complexes

Che, Chi‐Ming; Tse, Man-Chung; Chan, Michael C. W.; Cheung, Kung‐Kai; Phillips, and David Lee; Leung, King-Hung

doi:10.1021/ja9904890

Cited by 344 publications

(161 citation statements)

References 37 publications

(37 reference statements)

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“…[31][32][33] This is because coordination of ligand(s)/substrate to d 10 -metal ions, in both the ground and excited states, would weaken the closed-shell d 10 -d 10 metallophilic interactions and leads to the formation of an exciplex that emits at a similar or even lower energy than the emission directly from the metal-metal bonded 3 A C H T U N G T R E N N U N G [nds*A C H T U N G T R E N N U N G (n+1)ps] excited state. [34] The effect of coordination of ligand(s)/substrate to d 10 -metal ions on the spectroscopic properties of the 3 A C H T U N G T R E N N U N G [nds*A C H T U N G T R E N N U N G (n+1)ps] excited state would be more pronounced in polynuclear Ag I than Au I complexes, as a silver···silver interaction is considerably weaker than a gold···gold interaction.…”

Section: H T U N G T R E N N U N G (Dcmp) 2 CL 2 ]mentioning

confidence: 99%

“…[31,35] Thus, while 3 2 (dcpm = bis(cyclohexylphosphino)methane, and X is a counterion) has been reported, [11,12] the abnormally large Stokes shift between the absorption spectrum and the reported emission at l max % 420 nm of solid sample of [Ag 2 A C H T U N G T R E N N U N G (dcpm) 2 ][X] 2 (X = ClO 4 À or PF 6 À ) casts doubt as to whether the latter emission is directly from the metal-metal bonded 3 A C H T U N G T R E N N U N G [4ds*5ps] excited state or not. [32] One way to delineate this problem would be to prepare polynuclear d 10 -metal complexes with a linear array of metal ions. As the 3 …”

Section: H T U N G T R E N N U N G (Dcmp) 2 CL 2 ]mentioning

confidence: 99%

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The ³[ndσ*(n+1)pσ] Emissions of Linear Silver(I) and Gold(I) Chains with Bridging Phosphine Ligands

Tong

Kui

Chao

et al. 2009

Chemistry A European J

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The complexes [Au(3)(dcmp)(2)][X](3) {dcmp=bis(dicyclohexylphosphinomethyl)cyclohexylphosphine; X=Cl(-) (1), ClO(4) (-) (2), OTf(-) (3), PF(6) (-) (4), SCN(-)(5)}, [Ag(3)(dcmp)(2)][ClO(4)](3) (6), and [Ag(3)(dcmp)(2)Cl(2)][ClO(4)] (7) were prepared and their structures were determined by X-ray crystallography. Complexes 2-4 display a high-energy emission band with lambda(max) at 442-452 nm, whereas 1 and 5 display a low-energy emission with lambda(max) at 558-634 nm in both solid state and in dichloromethane at 298 K. The former is assigned to the (3)[5dsigma*6psigma] excited state of [Au(3)(dcmp)(2)](3+), whereas the latter is attributed to an exciplex formed between the (3)[5dsigma*6psigma] excited state of [Au(3)(dcmp)(2)](3+) and the counterions. In solid state, complex [Ag(3)(dcmp)(2)][ClO(4)](3) (6) displays an intense emission band at 375 nm with a Stokes shift of approximately 7200 cm(-1) from the (1)[4dsigma*-->5psigma] absorption band at 295 nm. The 375 nm emission band is assigned to the emission directly from the (3)[4dsigma(*)5psigma] excited state of 6. Density functional theory (DFT) calculations revealed that the absorption and emission energies are inversely proportional to the number of metal ions (n) in polynuclear Au(I) and Ag(I) linear chain complexes without close metalanion contacts. The emission energies are extrapolated to be 715 and 446 nm for the infinite linear Au(I) and Ag(I) chains, respectively, at metalmetal distances of about 2.93-3.02 A. A QM/MM calculation on the model [Au(3)(dcmp)(2)Cl(2)](+) system, with Au...Cl contacts of 2.90-3.10 A, gave optimized Au...Au distances of 2.99-3.11 A in its lowest triplet excited state and the emission energies were calculated to be at approximately 600-690 nm, which are assigned to a three-coordinate Au(I) site with its spectroscopic properties affected by Au(I)...Au(I) interactions.

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Section: H T U N G T R E N N U N G (Dcmp) 2 CL 2 ]mentioning

confidence: 99%

Section: H T U N G T R E N N U N G (Dcmp) 2 CL 2 ]mentioning

confidence: 99%

The ³[ndσ*(n+1)pσ] Emissions of Linear Silver(I) and Gold(I) Chains with Bridging Phosphine Ligands

Tong

Kui

Chao

et al. 2009

Chemistry A European J

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“…The triflimide was selected as aw eakly coordinating anion in order to lend lipophilic properties to the resulting salt. Nonetheless, the triflimide ions accept several weak hydrogen bonds from the [12,13], but here the distance betweenthe silver atoms(Ag×××Ag 4.478 Å) is safely beyond the range of any interaction. Symmetry codes: i:1+x, y, -1+z; ii:1-x,-y,-z; iii:x,y,-1+z; iv:1-x, 1-y,-z.…”

Section: Discussionmentioning

confidence: 98%

Crystal structure of bis-(1-(2-(diethylamino)ethyl)-3-methylimidazolin-2- ylidene) di-silver(I) bis-(triflimide), Ag2[C10H19N3]2[C2F6NO4S2]2, C24H38Ag2F12N8O8S4

Schottenberger

al.²

2012

Zeitschrift für Kristallographie - New Crystal Structures

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Source of materialThet itle compound was synthesized by stirring 1-(2-(diethylamino)ethyl)-3-methylimidazolium triflimide [1] and silver oxide in methanol. After filtration, single crystals were grown from the solution at -20°C. Experimental detailsIn thepresent case,the asymmetric unit contains one half molecule of thed icationicA gc omplex andt wo half units of the triflimide anions. The two triflimide molecules are located near an inversion centre and are disordered in aw ay which is not consistent with the symmetry operation of the inversion. For the first anion, we have a1:1 disorder with split atom positions for O1, O2, F1, F2, F3 and O1A, O2A, F1A, F2A, F3A. The nitrogen atom N4 lies near an inversion centre (occupancy 0.5). The complete anion is generated in two ways: S1-C11-O1-O2-F1-F2-F3-N4 connected with the inverted coordinates of S1-C11-O1A-O2A-F1A-F2A-F3A, or S1-C11-O1A-O2A-F1A-F2A-F3A connected with the inverted coordinates of N4-S1-C11-O1-O2-F1-F2-F3. The second anion shows even more disorder: one identical to the first anion, the second due to additional splitting of the S-and C-positions. Thus, four positions are possible. The occupancies are 0.75 for S2 and C12; 0.5 for N5, O3, O4, F4, F5, and F6; and 0.25 for O3A, O4A, F4A, F5A, F6A, S3, C13, O5, O6, F7,F8, and F9. With the exception of S3, the atomsofthe minor component were refined isotropically. Cation and anions are shown separately for clarity. DiscussionSilver N-heterocyclic carbene (NHC) complexes have received much attention, and their chemistry has been reviewed [2-4].The silver compounds are particularly well-suited precursors for otherm etal NHC systemsb yt ransmetallation. Thus, they bear potential in catalysis [5], fortheir optical properties [6][7][8], and as pharmaceuticals [9,10]. Bidentate amino-carbene ligands [11] often yield cyclic dinuclear metal complexes with interesting structural properties. The central metal-ligand bonds C1-Ag1 and N3-Ag1 are 2.073 and 2.178 Ålong, respectively, and deviate only slightly from linearity with aC 1-Ag1-N3 angle of 172.6°. The N1-C1-N2 'carbene angle' of 104.7°in this silver complex is in line with that observed in other imidazolin-2-ylidene-metal complexes (mean value 104.0°from 4185 related structures in the CSD), which is significantly smaller than the typical value in imidazolium salts (mean value 108.7°from 1202 cations in the CSD). The triflimide was selected as aw eakly coordinating anion in order to lend lipophilic properties to the resulting salt. Nonetheless, the triflimide ions accept several weak hydrogen bonds from the Z. Kristallogr.

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“…interactions have been observed in some multinuclear Ag(I) complexes. 40,41) The crystal of 2h formed a zigzag structure along the crystallographic a axis, with a pitch of 4.4377(3) Å (Fig. 2).…”

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confidence: 99%

Synthesis and Antimicrobial Activity of 2-Trifluoroacetonylbenzoxazole Ligands and Their Metal Complexes

et al. 2018

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Key words antibacterial activity; fluorinated benzoxazole; metal complex; trifluoroacetylBacterial infection remains a serious threat to human lives due to rapid development of resistance to the existing antibiotics. In order to prevent this major medical problem, the discovery of new types of antimicrobial agents is a very important but challenging task.1,2) Transition metal complexes have received great attention because many drugs such as antibiotics and quinolone antibiotics possess better pharmaceutical properties when they are in the form of metal complexes. 3-7)Benzoxazole heterocycle system is an important pharmacophore and privileged structure in the medicinal chemistry. 8-10)Its derivatives and particularly, 2-substituted benzoxazoles exert various biological activities such as antimicrobial, antiviral, antifungal, and anticancer. [11][12][13][14][15] In previous studies, we have identified 2-trifluoroacetonylbenzoxazole (1a) with in vitro antimicrobial activity against Helicobacter pylori and Escherichia coli (Ec) from our compound library of trifluoromethyl ketones obtained by our developed reactions. 16,17) The heteroaryl-substituted alkenol systems such as 1a are known to chelate some metal ions such as aluminum 18) and to form a stable six-membered metal complexes in a bidentate mode, where the complexes were reinforced by a positive inductive effect of the heterocyclic moiety and a negative inductive effect of the CF 3 groups. [19][20][21][22][23] In the light of these knowledge, three 2-fluoroacetonylbenzoxazole ligands 1a-c and their new Zn(II) complexes 2a-c have been synthesized in order to check how the metal ion binding may influence their antibacterial activity (Chart 1). In addition, syntheses of new metal [Mg(II), Ni(II), Cu(II), Pd(II), and Ag(I)] complexes 2d-h from 1a have been also described ( Table 1). The structures of six metal complexes 2b and 2d-h were determined by single-crystal X-ray diffraction analyses. In vitro antimicrobial activities of the ligands 1a-c and their metal complexes 2a-h were investigated against six Gram-positive (G(+)) and six Gram-negative (G(−)) bacteria and the results were compared with those of silver nitrate and appropriate antibiotics such as Kanamycin, Gentamicin, Norfloxacin, and/or Linezolid. The most potent Ag(I) complex 2h is bacteriostatic, disrupts membrane integrity observed by scanning electron microscopy (SEM) and is less likely to develop resistance development against Pseudomonas aeruginosa (Pa). Results and DiscussionChemistry First, three benzoxazole ligands 1a-c and their new Zn(II) complexes 2a-c have been prepared in order to investigate the relationship of the ligands and their Zn(II) complexes with their antibacterial activities.Our synthetic protocol to obtain the ligand 1a consists of a trifluoroacetylation of 2-methylbenzoxazole with trifluoroacetic anhydride (TFAA) in the presence of pyridine 24) (Chart 1). The Zn(II) complex 2a was prepared by the reaction of 1a with zinc dust in MeCN in 78% yield, consisting of 1a with zinc(...

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Spectroscopic Evidence for Argentophilicity in Structurally Characterized Luminescent Binuclear Silver(I) Complexes

Cited by 344 publications

References 37 publications

The ³[ndσ*(n+1)pσ] Emissions of Linear Silver(I) and Gold(I) Chains with Bridging Phosphine Ligands

The ³[ndσ*(n+1)pσ] Emissions of Linear Silver(I) and Gold(I) Chains with Bridging Phosphine Ligands

Crystal structure of bis-(1-(2-(diethylamino)ethyl)-3-methylimidazolin-2- ylidene) di-silver(I) bis-(triflimide), Ag2[C10H19N3]2[C2F6NO4S2]2, C24H38Ag2F12N8O8S4

Synthesis and Antimicrobial Activity of 2-Trifluoroacetonylbenzoxazole Ligands and Their Metal Complexes

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Spectroscopic Evidence for Argentophilicity in Structurally Characterized Luminescent Binuclear Silver(I) Complexes

Cited by 344 publications

References 37 publications

The 3[ndσ*(n+1)pσ] Emissions of Linear Silver(I) and Gold(I) Chains with Bridging Phosphine Ligands

The 3[ndσ*(n+1)pσ] Emissions of Linear Silver(I) and Gold(I) Chains with Bridging Phosphine Ligands

Crystal structure of bis-(1-(2-(diethylamino)ethyl)-3-methylimidazolin-2- ylidene) di-silver(I) bis-(triflimide), Ag2[C10H19N3]2[C2F6NO4S2]2, C24H38Ag2F12N8O8S4

Synthesis and Antimicrobial Activity of 2-Trifluoroacetonylbenzoxazole Ligands and Their Metal Complexes

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The ³[ndσ*(n+1)pσ] Emissions of Linear Silver(I) and Gold(I) Chains with Bridging Phosphine Ligands

The ³[ndσ*(n+1)pσ] Emissions of Linear Silver(I) and Gold(I) Chains with Bridging Phosphine Ligands