Stability and kinetics of G-quadruplex structures

In this review, we give an overview of recent literature on the structure and stability of unimolecular G-rich quadruplex structures that are relevant to drug design and for in vivo function. The unifying theme in this review is energetics. The thermodynamic stability of quadruplexes has not been studied in the same detail as DNA and RNA duplexes, and there are important differences in the balance of forces between these classes of folded oligonucleotides. We provide an overview of the principles of stability and where available the experimental data that report on these principles. Significant gaps in the literature have been identified, that should be filled by a systematic study of well-defined quadruplexes not only to provide the basic understanding of stability both for design purposes, but also as it relates to in vivo occurrence of quadruplexes. Techniques that are commonly applied to the determination of the structure, stability and folding are discussed in terms of information content and limitations. Quadruplex structures fold and unfold comparatively slowly, and DNA unwinding events associated with transcription and replication may be operating far from equilibrium. The kinetics of formation and resolution of quadruplexes, and methodologies are discussed in the context of stability and their possible biological occurrence

Intrinsic triple-emitting 2D copper thiolate coordination polymer as a ratiometric thermometer working over 400 K range

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Structural and photophysical studies of Au(I)-thiolate coordination polymers

SSCI-VIDE+CDFA+OVE:ADMNational audienceHybrid Au(I) compounds exhibit a large domain of applications such as electronic devices,contrast agents, sensors or photocatalysts. These applications are related to the ability of gold(I) to form aurophilic interactions implying luminescence.[1] Among them, gold(I) thiolates are an important class of materials, that can generate oligomeric or polymeric structures due to the high affinity of gold for sulfur atoms. This also implies a high reactivity between thiols gold precursor and the formation of insoluble products. Thus, a little is known about their structure and the origin of the photophysical properties. Only three crystallographic structures of gold(I) thiolates coordination polymers have been reported: two having double interpenetrated helical chains[2] and one having a lamellar structure.[3] Among them two exhibit red photo-emission with extreme quantum yields of around 5 and 70 % in solid state at room temperature. Thus, a little is known about the origin of the photoluminescence of gold thiolate coordination polymers and the relation with the structure and the effect of the ligands. Here we present syntheses and structure resolutions by powder X-Ray diffraction of three new Au(I)-thiophenolate-based lamellar compounds: [Au(oSPhNH2)]n, [Au(pSPhCOOH)]n and [Au(mSPhCOOH)]n. The first one, amino function, forms double interpenetrated helicalchains, as already reported [Au(SPh)]n,[2] but is emissive in the near infra-red. The two other compounds with carboxylic acids in para and meta position have lamellar structures with a quite similar helical and parallel Au(I)-S chains (Fig. 1). Nevertheless, aurophilic distances between the chains are a bit different. Thus, despite the structures are quite similar, the photophysical properties are different. [Au(mSPhCOOH)]n exhibits only one emission peak centered at 600 nm that originates from Ligand-to-Metal-to-Ligand Charge Transfer, meanwhile [Au(pSPhCOOH)]n shows dual emission with peaks at 495 and 650nm that originate from Ligand Charge Transfer and Ligand-to-Metal-to-Metal Charge Transfer respectively.The study shows for the first time the sensitivity and richness of structures and photophysicalproperties of gold thiolate coordination polymers. With this high tunability we valorize these materials as either lighting applications or as an optical thermometer with the thermochromic solid.References1. H. Schmidbaur, A. Schier, Chem. Soc. Rev., 2012, 41, 370-412.2. C. Lavenn, L. Okhrimenko, N. Guillou, M. Monge, G. Ledoux, C. Dujardin, R. Chiriac, A. Fateeva, A. Demessence, J. Mater. Chem. C, 2015, 3, 4115-4125.3. C. Lavenn, N. Guillou, M. Monge, D. Podbevšek, G. Ledoux, A. Fateeva, A. Demessence, Chem. Commun., 2016, 52, 9063-9066

Structural and photophysical studies of lamellar M(I)-thiophenolate coordination polymers (M = Au, Ag, Cu)

SSCI-VIDE+CDFA+OVE:ADMNational audienceMetal thiolate compounds represent a large family of materials including nanoparticles, self-assembled monolayers and oligomeric/polymeric species showing diverse properties and applications. Among them [M(I)(SR)]n coordination polymers have been studied for a long time, for example hybrid Au(I) compounds have been used as anti arthritic drugs; Ag(I) compounds are known for their antibacterial properties[1] and Cu(I) compounds were recently shown to be good electrical conductors.[2] Moreover, these materials present great interest due to their ability to form metalophilic interactions which often imply luminescence.[3] However, despite interesting properties and potential applications, little is known about their structures. Indeed, the high affinity of M(I) for sulfur atoms implies a high reactivity between thiols and metal precursors and the formation of insoluble products.Metal thiolate phases, when the metal is Cu, Ag and Au, described in the literature can be classified according to the dimensionality of the -M(I)-S- motive into 0D, 1D and 2D-structures. The lamellar compounds are well-known, but only three structures are reported: [Au(pSPhCO2CH3)]n, [Ag(othiopyridine)]n, [Cu(pSPhOH)]n. The structure of [Au(pSPhCO2CH3)]n has been recently solved by powder X-Ray diffraction and exhibits an ultra-bright luminescence with a quantum yield over 70 % at room temperature in solid state.[4] From this result, we extended this study to other lamellar M(I)-thiophenolate coordination polymers. We will present the syntheses and structure resolutions by powder and single crystal X-Ray diffraction of series of 5 new M(I)-thiophenolate-based compounds [M(I)(pSPhCO2X)]n (M = Au, Ag, Cu and X = H and CH3). We will show how the presence of weak interactions can impact the structure and photophysical properties. In addition, some of these compounds show thermochromism with intrinsic dual emission. So, we will discuss their high potential as optical ratiometric thermometers exhibiting some of the best sensitivity parameters exceeding the performances of the lanthanide-based hybrid coordination polymers.References:[1] B. O. Leung, F. Jalilehvand, V. Mah, M. Parvez, Q. Wu, Inorg. Chem. 2013, 52, 4593-4602.[2] H. Yan, J. N. Hohman, F. H. Li, C. Jia, D. Solis-Ibarra, B. Wu, J. E. P. Dahl, R. M. K. Carlson, B. A. Tkachenko, A. A. Fokin, Nature materials, 2016.[3] H. Schmidbaur, A. Schier, Chem. Soc. Rev., 2012, 41, 370-412.[4] C. Lavenn, N. Guillou, M. Monge, D. Podbevšek, G. Ledoux, A. Fateeva, A. Demessence, Chem. Commun., 2016, 52, 9063-9066

Structure and photophysical properties of a series of new 1D d 10 Coinage Metal Organic Chalcogenolates (MOCs): [M(o-SPhCO2H)]n (M = Cu, Ag, Au)

SSCI-VIDE+CDFA+OVE:ADMInternational audienceThiosalicylic acid is hard-soft donor ligand, able to coordinate numerous metals [1]. A significant number of coordination compounds of d10 metals have been reported. However, crystallographic studies of polymeric species stayed very limited compared to their mono- and oligomeric counterparts. For example, preparation of polymeric [Au(oSCPhCO2H)]n has been reported [2], as well as polymeric compounds of silver thiosalicylate [3], but no crystallographic structure was reported. A number of Cu(II) thiosalicylates [4], a mixed-valence Cu(I)2Cu(II) complex [5] and no Cu(I) complexes have been described up to our knowledge. In most cases structural studies are precluded due to the strong affinity between sulfur and coinage metals, inducing a rapid precipitation of coordination polymers making single crystals hardly obtainable. In presented work, we report extensive pioneering structural study of three polymeric species of Cu(I), Au(I) and Ag(I). Structural study was performed by means of powder X-ray diffraction and PDF (pair distribution function) calculations. These coordination polymers have similar 1D structures. Based on this fact, we are able to discuss the influence of the structure and the nature of the metallic ion on photophysical properties of these materials. They emin in orange to NIR part of the spectrum. High quantum yields make them interesting for illumination and as NIR-emitters. [1] T. Wehr-Candler et al. Coord. Chem. Rev. 2016, 313, 111.[2] R.E. Bachman et al. Z. Naturforsch. 2009, 64B, 1491. [3] K. Nomiya et al. J. Inorg. Biochem. 1995, 58, 255. [4] See for example M.S. Abu-Bakr, Monatsh. Chem. 1997, 128, 563. [5] R.C. Bott et al. Chem. Commun. 1998, 2403

Structural Diversity of Coordination Polymers Based on a Heterotopic Ligand: Cu(II)-Carboxylate vs Cu(I)-Thiolate

SSCI-VIDE+CDFA+OVE:ADMInternational audienceTwo copper(II)-carboxylate disulfide coordination polymers [Cu2((O2CPhS)2)2(H2O)2]n (1, 2) and one copper(I)-thiolate coordination polymer [Cu(p-SPhCO2H)]n (3) have been synthesized using either the 4-mercaptobenzoic acid (HSPhCO2H) or the 4,4′-dithiodibenzoic acid ((SPhCO2H)2) as ligand. These three compounds were characterized by X-ray diffraction, IR, and thermogravimetric analyses. Compounds 1 and 2 are polymorphs with the presence, for both, of dinuclear paddle-wheel copper(II)-carboxylates. In 1, the adjacent dimeric Cu2 units are linked by two (O2CPhS)2 ligands generating a cyclic loop chain, and in 2, each pair of Cu (II) atoms is linked by four ligands to create 2D networks, that are 2-fold interpenetrated. Compound 3 presents a lamellar structure, with an exceptional thermal and chemical stability, and exhibits intrinsic multiple emission between 485 and 660 nm. The different intensities of these bands generate a cyclic luminescence thermochromism from yellow to green to yellow

Shedding light on an ultra-bright photoluminescent lamellar gold thiolate coordination polymer Au(p-SPhCO2Me) (n)

SSCI-VIDE+CDFA+CLA:MMO:ADMInternational audienceThe first structure elucidation of a lamellar gold thiolate coordination polymer is described. [Au(p-SPhCO2Me)](n) is obtained from the simultaneous esterification of mercaptobenzoic acid and reduction of the Au(III) precursor. Despite the presence of aurophilic interactions, the intense phosphorescence (QY similar to 70%) originates from intra-ligand and metal-to-ligand transitions

New Lamellar Silver Thiolate Coordination Polymers with Tunable Photoluminescence Energies by Metal Substitution

SSCI-VIDE+CDFA:ECI2D+OVE:DEC:ADMInternational audienceThe structures of two lamellar silver thiolate coordination polymers [Ag(p-SPhCO2H)]n (1) and [Ag(p-SPhCO2Me)]n (2) are described for the first time. Their inorganic part is composed of distorted Ag3S3 honeycomb networks separated by noninterpenetrated thiolate ligands. The main difference between the two compounds arises from dimeric hydrogen bonds present for the carboxylic acids. Indepth photophysical studies show that the silver thiolates exhibit multiemission properties, implying luminescence thermochromism. More interestingly, the synthesis of a heterometallic lamellar compound, [Ag0.85Cu0.15(p-SPhCO2H)]n (3), allows to obtain mixed metal thiolate coordination polymers and to tune the photophysical properties with the excitation wavelengths from a green vibronic luminescence to a single red emission band

An intrinsic dual-emitting gold thiolate coordination polymer, [Au( plus I)(p-SPhCO2H)](n), for ratiometric temperature sensing

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