Luminescence color switching of supramolecular assemblies of discrete molecular decanuclear gold(I) sulfido complexes.

A series of discrete decanuclear gold(I) µ(3)-sulfido complexes with alkyl chains of various lengths on the aminodiphosphine ligands, [Au(10){Ph(2)PN(C(n)H2(n+1))PPh(2)}(4)(µ(3)-S)(4)](ClO(4))(2), has been synthesized and characterized. These complexes have been shown to form supramolecular nanoaggregate assemblies upon solvent modulation. The photoluminescence (PL) colors of the nanoaggregates can be switched from green to yellow to red by varying the solvent systems from which they are formed. The PL color variation was investigated and correlated with the nanostructured morphological transformation from the spherical shape to the cube as observed by transmission electron microscopy and scanning electron microscopy. Such variations in PL colors have not been observed in their analogous complexes with short alkyl chains, suggesting that the long alkyl chains would play a key role in governing the supramolecular nanoaggregate assembly and the emission properties of the decanuclear gold(I) sulfido complexes. The long hydrophobic alkyl chains are believed to induce the formation of supramolecular nanoaggregate assemblies with different morphologies and packing densities under different solvent systems, leading to a change in the extent of Au(I)-Au(I) interactions, rigidity, and emission properties.

Cleavage of a P-N Bond in a Urea-Containing (Ph2 P(R)PPh2 )-Bridged Dinuclear Gold(I) Thiolate Complex by Fluoride and a Mechanistic Insight.

A urea-containing, (Ph2 P(R)PPh2 )-bridged, dinuclear, gold(I) thiolate complex, [Au2 {Ph2 PN(C6 H4 OMe-4)PPh2 }(SC6 H4 NHCONHC6 H5 )2 ] (1) was designed and synthesized and its photophysical and anion recognition properties studied. The results show that 1 has a high selectivity toward F(-) . Upon addition of F(-) , the yellow solution was decolorized, and drastic changes of emission and (1) H and (31) P{(1) H} NMR signals were observed. Interestingly, these changes are attributed to fluoride-assisted P-N bond hydrolysis, instead of the expected hydrogen-bonding interactions with the urea receptor. Similar changes were observed for two other basic anions, AcO(-) and H2 PO4 (-) , but to a much lesser extent; and these anions were found to bind to the urea receptor at the same time. On the other hand, Cl(-) was found to only bind to the urea moiety through hydrogen-bonding interactions. Further studies with the control complex [Au2 {Ph2 PN(C6 H4 OMe-4)PPh2 }Cl2 ] (2) indicate that F(-) assists the hydrolysis process via cleavage of the P-N bond. DFT calculations were performed to study the reaction mechanism for the fluoride-assisted P-N bond hydrolysis of 2; these provide a better insight into the role of fluoride in the hydrolysis.

S1 certification of alpha-endosulfan, beta-endosulfan, and endosulfan sulfate in a candidate certified reference material (organochlorine pesticides in tea) by isotope dilution gas chromatography-mass spectrometry.

This paper presents the certification of alpha-endosulfan, beta-endosulfan, and endosulfan sulfate in a candidate tea certified reference material (code: GLHK-11-03) according to the requirements of the ISO Guide 30 series. Certification of GLHK-11-03 was based on an analytical method purposely developed for the accurate measurement of the mass fraction of the target analytes in the material. An isotope dilution mass spectrometry (IDMS) method involving determination by (i) gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS) and (ii) gas chromatography-electron ionization-high-resolution mass spectrometry (GC-EI-HRMS) techniques was employed. The performance of the described method was demonstrated through participation in the key comparison CCQM-K95 "Mid-Polarity Analytes in Food Matrix: Mid-Polarity Pesticides in Tea" organized by the Consultative Committee for Amount of Substance-Metrology in Chemistry in 2012, where the study material was the same as the certified reference material (CRM). The values reported by using the developed method were in good agreement with the key comparison reference value (KCRV) assigned for beta-endosulfan (727 ± 14 µg kg(-1)) and endosulfan sulfate (505 ± 11 µg kg(-1)), where the degree of equivalence (DoE) values were 0.41 and 0.40, respectively. The certified values of alpha-endosulfan, beta-endosulfan, and endosulfan sulfate in dry mass fraction in GLHK-11-03 were 350, 730, and 502 µg kg(-1), respectively, and the respective expanded uncertainties, due to sample inhomogeneity, long-term and short-term stability, and variability in the characterization procedure, were 27 µg kg(-1) (7.8 %), 48 µg kg(-1) (6.6 %), and 33 µg kg(-1) (6.6 %).

Hexanuclear gold(I) phosphide complexes as platforms for multiple redox-active ferrocenyl units.

The synthesis, X-ray crystal structures, electrochemical, and spectroscopic studies of a series of hexanuclear gold(I) µ(3)-ferrocenylmethylphosphido complexes stabilized by bridging phosphine ligands, [Au(6)(P-P)(n)(Fc-CH(2)-P)(2)][PF(6)](2) (n=3, P-P=dppm (bis(diphenylphosphino)methane) (1), dppe (1,2-bis(diphenylphosphino)ethane) (2), dppp (1,3-bis(diphenylphosphino)propane) (3), Ph(2)PN(C(3)H(7))-PPh(2) (4), Ph(2)PN(Ph-CH(3)-p)PPh(2) (5), dppf (1,1'-bis(diphenylphosphino)ferrocene) (6); n=2, P-P=dpepp (bis(2-diphenylphosphinoethyl)phenylphosphine) (7)), as platforms for multiple redox-active ferrocenyl units, are reported. The investigation of the structural changes of the clusters has been probed by introducing different bridging phosphine ligands. This class of gold(I) µ(3)-ferrocenylmethylphosphido complexes has been found to exhibit one reversible oxidation couple, suggestive of the absence of electronic communication between the ferrocene units through the Au(6)P(2) cluster core, providing an understanding of the electronic properties of the hexanuclear Au(I) cluster linkage. The present complexes also serve as an ideal system for the design of multi-electron reservoir and molecular battery systems.

Synthesis, characterization, and luminescence studies of discrete polynuclear gold(I) sulfido and selenido complexes with intramolecular aurophilic contacts.

The synthesis, characterization, and photophysical and photochemical properties of a family of high-nuclearity gold(I) chalcogenides, specifically, the gold(I) sulfido and selenido complexes containing different bridging diphosphine ligands with nuclearities of ten ([Au10{µ-Ph2PN(R)PPh2}4(µ3-E)4](2+)) and six ([Au6{µ-Ph2PN(R)PPh2}3(µ3-E)2](2+)), are reported. The X-ray crystal structures of the complex cations of Au10 and Au6 are found to be propeller-like structures and distorted cubane structures, respectively, with the presence of short intramolecular gold···gold distances. The complexes show intense green and/or orange phosphorescence upon photoexcitation in the solid state and in solution at ambient and low temperature. The emission properties are found to be strongly dependent on the nuclearities and the chalcogenido ligands, but are rather insensitive to the substituents on the bis(diphenylphosphino)amines. The emissions are tentatively assigned to originate from the excited states derived from the phosphine-centered intraligand (IL) transition or metal-centered (ds/dp) mixed with ligand-to-metal-metal charge transfer (LMMCT) (E→Au) transition. The photochemical properties of the complexes were also studied by transient absorption spectroscopy.

Unprecedented near-infrared (NIR) emission in diplatinum(III) (d7-d7) complexes at room temperature.

The synthesis and single-crystal X-ray structures of the first family of efficient NIR emitters with tunable emission energy based on dihalodiplatinum(III) (5d(7)-5d(7)) complexes of general formulae [Pt(2)(mu-C(6)H(3)-5-R-2-AsPh(2))(4)X(2)] (R = Me or CHMe(2); X = Cl, Br or I), together with that of their diplatinum(II) (5d(8)-5d(8)) precursors ([Pt(2)(mu-C(6)H(3)-5-R-2-AsPh(2))(4)]) and cyano counterparts (X = CN), are reported. The diplatinum(II) complexes with isopropyl groups are isolated initially as a mixture of two species, one being a half-lantern structure containing two bridging and two chelate C(6)H(3)-5-CHMe(2)-2-AsPh(2) ligands (1b) that exists in two crystalline modifications [d(Pt...Pt) = 3.4298(2) A and 4.3843(2) A]; the other is a full-lantern or paddle-wheel structure having four bridging C(6)H(3)-5-CHMe(2)-2-AsPh(2) ligands (2b) [d(Pt...Pt) = 2.94795(12) A]. Complete conversion of the isomers into 2b occurs in hot toluene. The Pt-Pt bond distances in the diplatinum(III) complexes are less than that in 2b and increase in the order X = Cl (3b) [2.6896(2) A] < Br (4b) [2.7526(3) A] < I (5b) [2.7927(7) A] approximately CN (6b) [2.7823(2), 2.7924(2) A for two independent molecules]. Comparison with the corresponding data for our previously reported series of complexes 3a-6a (R = Me) indicates that the Pt-Pt bond lengths obtained from single-crystal X-ray analysis are influenced both by the axial ligand and by intermolecular lattice effects. Like [Pt(2)(mu-pop)(4)](4-) [pop = pyrophosphite, (P(2)O(5)H(2))(2-)], the diplatinum(II) complexes [Pt(2)(mu-C(6)H(3)-5-R-2-AsPh(2))(4)] [R = Me (2a), CHMe(2) (2b)] display intense green phosphorescence, both as solids and in solution, and at room temperature and 77 K, with the emission maxima in the range 501-532 nm. In contrast to the reported dihalodiplatinum(III) complexes [Pt(2)(mu-pop)(4)X(2)](4-) that exhibit red luminescence only at 77 K in a glass or as a solid, complexes 3a-6a and 3b-6b are phosphorescent in the visible to near-infrared region at both room and low temperatures. The electronic spectra and photoemissive behavior are discussed on the basis of time-dependent density functional theory (TDDFT) calculations at the B3YLP level. The photoemissive states for the halide analogues 3a,b-5a,b involve a moderate to extensive mixing of XMMCT character and MC [d sigma-d sigma*] character, whereas the cyano complexes 6a and 6b are thought to involve relatively less mixing of the XMMCT character into the MC [d sigma-d sigma*] state.

Design, synthesis, photophysics, and anion-binding studies of bis(dicyclohexylphosphino)methane-containing dinuclear gold(I) thiolate complexes with urea receptors.

A series of bis(dicyclohexylphosphino)methane (dcpm)-containing gold(I) thiolate complexes with urea receptors, 1-3, has been successfully designed and synthesized, and their photophysical and anion-binding properties have been studied. The linker between the thiolate and the urea group, and the electronic environment of the urea moiety, have been found to exert a great influence on the photophysical and anion-binding properties of the complexes. Complex 3 displays an intense long-lived orange-red luminescence at around 620 nm in the solid state and in the glass state at 77 K, which is considerably red shifted from the band seen in a solution of dichloromethane at room temperature, suggesting the presence of AuAu interactions. Upon introducing an electron-withdrawing NO(2) group, complex 1 was found to show high selectivity and sensitivity for F(-) through a drastic color change from yellow to red. The anion-binding constants of the complexes have been determined from electronic absorption and (1)H NMR spectroscopy titration studies and the data were found to fit well to a 1:1 binding model for the interactions between the complexes and the anions. Complexes 1 and 2 show the same anion selectivity trend of F(-) > AcO(-) > H(2)PO(4)(-) > Cl(-) approximately Br(-) approximately I(-), which is consistent with the trend in anion basicity. In addition, complex 1 has been shown to exhibit higher binding affinity for anions compared with those of complexes 2 and 3, probably due to the higher acidity of the urea moiety as a result of the introduction of the NO(2) group.

Selective ion probe for Mg2+ based on Au(I)Au(I) interactions in a tripodal alkynylgold(I) complex with oligoether pendants.

A simple but novel tripodal alkynylgold(I) complex with oligoether pendants has been synthesized and demonstrated to be a selective ion probe for Mg2+ based on Au(I)Au(I) interactions.

Self-assembly of a neutral luminescent Au(12) cluster with D(2) symmetry.

The preparation and characterization of luminescent neutral Au(12) shuttle-like complexes is reported which shows a cyclic framework consisting of twelve gold(i) ions arranged in a closed ring via non-covalent Au(i)Au(i) interactions to give a chiral D(2) symmetrical structure.

Highlights on the recent advances in gold chemistry--a photophysical perspective.

The presence of inter- and/or intra-molecular aurophilic interactions among the closed-shell gold(I) centres in various systems has been studied from various aspects, including synthetic, spectroscopic and theoretical approaches. The employment of different ligands can impose a significant influence on these factors and give rise to new complexes with interesting structural and photophysical properties. In this tutorial review, a number of recent examples are selected to illustrate the fascinating properties and chemistry, as well as versatility of gold(I) in these aspects and their potential applications to newcomers in this field. An emerging class of luminescent gold(III) complexes is also described.

Synthesis, luminescence and ion-binding properties of palladium(II) complexes with 1,2-bis[di(benzo-15-crown-5)phosphino]ethane (dbcpe).

A series of palladium(II) complexes with 1,2-bis[di(benzo-15-crown-5)phosphino]ethane ligand (dbcpe), [Pd(dbcpe)X2] (X = Cl 1, Br 2 and I 3), have been successfully synthesised and characterised. The X-ray crystal structure of dbcpe has also been determined. The cation-binding properties of the complexes have been studied and the stability constants with alkali metal cations determined. The crown-free analogue of dbcpe, 1,2-bis[bis(3,4-dimethoxyphenyl)phosphino]ethane (ddmppe), and the related complexes have also been prepared and comparison studies have been made.

Computational studies on the photophysical properties and NMR fluxionality of the tetranuclear copper(I) complexes [Cu4(mu-dppm)4(mu4-E)]2+ (E = PPh and S).

Density functional theory (DFT) calculations at the hybrid Perdew, Burke, and Ernzerhof functional level were performed to study the electronic structures of the ground and excited states of the luminescent tetranuclear copper(I) complexes [Cu4(mu-dppm)4(mu4-E)]2+ [E = PPh (1) and S (2)] by using model complexes [Cu4(mu-H2PCH2PH2)4(mu4-E)]2+ [E = PPh (1a) and S (2a)]. The time-dependent DFT method at the same level associated with the conductor-like polarizable continuum model was used to study the nature of the low-energy transitions in their electronic absorption spectra. The results indicate that the lowest energy absorptions of both 1 and 2 are attributed to ligand-to-metal charge-transfer (LMCT) (E --> Cu4) with mixing of metal-cluster-centered (MCC) (3d --> 4s/3d --> 4p) singlet-singlet transitions. The geometry optimizations on the lowest energy triplet state reveal that the emissive states of both complexes involve a considerable structural distortion in which they are derived predominantly from an admixture of 3LMCT (E --> Cu4) and 3MCC (3d --> 4p) origin. In addition to the photophysical properties, the fluxional behavior of 2 observed from the NMR studies but not that of 1 was investigated. It is found that the fluxionality in 2 involves the shuttling of the sulfido ligand through the rectangular Cu4 core.

Luminescent phosphine gold(I) thiolates: correlation between crystal structure and photoluminescent properties in [R3PAu{SC(OMe)=NC6H4NO2-4}] (R = Et, Cy, Ph) and [(Ph2P-R-PPh2){AuSC(OMe)=NC6H4NO2-4}2] (R = CH2, (CH2)2, (CH2)3, (CH2)4, Fc).

X-ray crystallography shows the gold atoms in [R3PAu{SC(OMe)=NC6H4NO2-4}] (R = Et, Cy, Ph; 1-3, respectively) and [(Ph2P-R-PPh2){AuSC(OMe)=NC6H4NO2-4}(2)] (R = CH2, (CH2)2, (CH2)3, (CH2)4, Fc; 4-8, respectively) are linearly coordinated by phosphorus and thiolate-sulfur; weak intramolecular Au...O interactions are featured in all structures. The smaller ethyl substituents in 1 allow for supramolecular association via Au...S and Au...Au interactions that are not found in 2 and 3, which contain larger phosphorus-bound Cy and Ph groups, respectively. Intramolecular Au...Au interactions are found in the dppm, dppe, dppp, and Fc structures but not in the dppp analogue, for which an anti conformation was found. The structures have been correlated with the results from photophysical study conducted in the solid state. Thus, photoexcitation of 1-7 with lambda > 350 in the solid state and in solution produces green and blue luminescence, respectively. The spectra in each medium are remarkably similar to each other, and so the emission energy and excitation maxima observed for 1-7 appear to be independent of the nature of the ancillary phosphines, as well as the presence or absence of Au...Au interactions, either intermolecularly or intramolecularly.

Luminescent molecular copper(I) alkynyl open cubes: synthesis, structural characterization, electronic structure, photophysics, and photochemistry.

A novel class of tetranuclear copper(I) alkynyl complexes with an "open-cube" structure was synthesized. The crystal structure of [Cu4{P(p-MeC6H4)3}4(mu3-eta(1),eta(1),eta(2)-C[triple bond]C-p-MeOC6H4)3]PF6 was determined. These complexes were found to display dual emission behavior. Through systematic comparison studies on the electronic absorption and photoluminescence properties of a series of [Cu4(PR3)4(mu3-eta(1),eta(1),eta(2)-C[triple bond]CR')3]+ complexes, together with density functional theory (DFT) calculations at the PBE1PBE level on the model complex [Cu4(PH3)4(mu3-eta(1),eta(1),eta(2)-C[triple bond]C-p-MeOC6H4)3]+, the nature of their emission origins was probed. Their photochemical properties were also investigated by oxidative quenching experiments and transient absorption spectroscopy.

A chiral luminescent Au16 ring self-assembled from achiral components.

A luminescent supramolecular chiral Au16 ring with 4.822 nm perimeter that self-assembled from a tetrameric array of achiral Au2 units is described. Intra- and intermolecular Au...Au interactions play an important role in directing its chiral self-assembly.

Syntheses, structural characterization, and host-guest chemistry of ethynylcrown ether containing polynuclear gold(I) complexes.

Two novel ethynylcrown ether containing di- and tetranuclear gold(I) complexes have been synthesized and structurally characterized; their binding ability toward various metal ions has also been studied.

Luminescent homo- and heteropolynuclear platinum(II) chalcogenido aggregates based on [Pt2E2(P empty set N)4] units (E=S, Se).

A series of homodinuclear platinum(II) complexes containing bridging chalcogenido ligands, [Pt(2)(mu-E)(2)(P empty set N)(4)] (P empty set N=dppy, E=S (1), Se (2); P empty set N=tBu-dppy, E=S (3)) (dppy=2-(diphenylphosphino)pyridine, tBu-dppy=4-tert-butyl-2-(diphenylphosphino)pyridine) have been synthesized and characterized. The nucleophilicity of the [Pt(2)E(2)] unit towards a number of d(10) metal ions and complexes has been demonstrated through the successful isolation of a number of novel heteropolynuclear platinum(II)-copper(I), -silver(I), and -gold(I) complexes: [[Pt(2)(mu(3)-E)(2)(dppy)(4)](2)Ag(3)](PF(6))(3) (E=S (4); Se (5)) and [Pt(2)(dppy)(4)(mu(3)-E)(2)M(2)(dppm)]X(2) (E=S, M=Ag, X=BF(4) (6); E=S, M=Cu, X=PF(6) (7); E=S, M=Au, X=PF(6) (8); E=Se, M=Ag, X=PF(6) (9); E=Se, M=Au, X=PF(6) (10)). Some of them display short metal.metal contacts. These complexes have been found to possess interesting luminescence properties. Through systematic comparison studies, the emission origin has been probed.