Cyclic Solid-State Multiple Phase Changes with Tuned Photoemission in a Gold Thiolate Coordination Polymer.

The discovery of a universal memory that exhibits fast access speed, high-density storage, and non-volatility has fuelled research into phase-change materials over the past decades. In spite of the efficiency of the inorganic chalcogenides for phase-change random access memory (PCRAM), they still have some inherent drawbacks, such as high temperature required for phase change and difficulty to control the domain size of the phase change, because of their brittleness. Here we present a AuI -thiolate coordination polymer which undergoes two successive phase changes on application of mild heating (<200 °C) from amorphous-to-crystalline1-to-crystalline2 phases. These transitions are reversible upon soft hand grinding. More importantly, each phase exhibits different photoluminescent properties for an efficient optical read-out. We believe that the ability of the AuI -thiolate coordination polymer to have reversible phase changes under soft conditions and at the same time to display distinct optical signals, can pave the way for the next generation of PCRAM.

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

The 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.

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

Two 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.

Transparent and luminescent glasses of gold thiolate coordination polymers.

Obtaining transparent glasses made of functional coordination polymers (CPs) represents a tremendous opportunity for optical applications. In this context, the first transparent and red-emissive glasses of gold thiolate CPs have been obtained by simply applying mechanical pressure to amorphous powders of CPs. The three gold-based CP glasses are composed of either thiophenolate [Au(SPh)] n , phenylmethanethiolate [Au(SMePh)] n or phenylethanethiolate [Au(SEtPh)] n . The presence of a longer alkyl chain between the thiolate and the phenyl ring led to the formation of glass with higher transparency. The glass transitions, measured by thermomechanical analysis (TMA), occurred at lower temperature for CPs with longer alkyl chains. In addition, all three gold thiolate glasses exhibit red emission at 93 K and one of them, [Au(SMePh)] n , remains luminescent even at room temperature. An in-depth structural study of the amorphous gold thiolates by XRD, PDF and EXAFS analysis showed that they are formed of disordered doubly interpenetrated helical chains. These d10 metal-based compounds represent the first examples of transparent and luminescent CP glasses.

A New Lamellar Gold Thiolate Coordination Polymer, [Au(m-SPhCO2H)]n, for the Formation of Luminescent Polymer Composites.

The photoluminescence of gold thiolate clusters brings about many potential applications, but its origin is still elusive because of its complexity. A strategy in understanding the structure-properties relationship is to study closely related neutral gold thiolate coordination polymers (CPs). Here, a new CP is reported, [Au(m-SPhCO2H)]n. Its structure is lamellar with an inorganic layer made of Au-S-Au-S helical chains, similar to the [Au(p-SPhCO2H)]n analog. An in-depth study of its photophysical properties revealed that it is a bright yellow phosphorescent emitter with a band centered at 615 nm and a quantum yield (QY) of 19% at room temperature and in a solid state. More importantly, a comparison to the para-analog, which has a weak emission, displayed a strong effect of the position of the electron withdrawing group (EWG) on the luminescent properties. In addition, [Au(m-SPhCO2H)]n CPs were mixed with organic polymers to generate transparent and flexible luminescent thin films. The ability to tune the emission position with the appropriate contents makes these nontoxic polymer composites promising materials for lighting devices.

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

A copper thiolate coordination polymer, [Cu(p-SPhCO2Me)]n, is described and exhibits, under UV, luminescence thermochromism, associated to a unique well-separated triple emission. This compound is the most promising candidate as a ratiometric temperature sensor, working in a wide temperature range, from 100 to 500 K, with a great sensitivity.