Transparent and luminescent glasses of gold thiolate coordination polymers

Low mechanical pressure on amorphous gold thiolate coordination polymers allows the formation of transparent and red emissive glasses.


TMA
A TMA/SDTA 840 from Mettler-Toledo has been used for the TMA measurements. The samples have been heated between 30 and 120°C at a heating rate of 3 or 5°C/min under an applied force of 0.01 or 0.1 N. The sample has been inserted between two quartz disks and the obtained « sandwich » was directly put inside the sample holder. The measuring probe used to apply the force was of 3 mm ball-point type in quartz glass, because of its low coefficient of thermal expansion and its high thermal stability. TMA was used in compression mode under air, which allows to use a homogenous force on all the surface of the sample by means of the quartz disk between the probe and the sample.

SEM
SEM images were obtained by FEI Quanta 250 FEG scanning electron microscope.
Samples were mounted on stainless pads and sputtered with Au/Pd alloy to prevent charging during observation.

Transmittance
Transmission measurement were performed on a Perkin Elmer UV/vis/NIR lambda 900 spectrometer with a limiting diaphragm of 1 mm and a resolution of 1 nm.

Photoluminescence measurements
The photoluminescence measurements were performed on a homemade apparatus. The sample was deposited on a silicon substrate to form a small mound of 4 mm in diameter and of ~1 mm in thickness. It was illuminated by an EQ99X laser driven light source filtered by a Jobin Yvon Gemini 180 monochromator. The exit slit from the monochromator was then reimaged on the sample by two 100m focal length, 2 inch diameter MgF2 lenses. The whole apparatus has been calibrated by means of a Newport 918D low power calibrated photodiode sensor over the range 190-1000 nm. The resolution of the system is 4 nm. The emitted light from the sample is collected by an optical fiber connected to a Jobin-Yvon TRIAX320 monochromator equipped with a cooled CCD detector. At the entrance of the monochromator, various long pass filters can be chosen to eliminate the excitation light. The wavelength dependence of the detection system was previously calibrated using a NIST calibrated QTH 45W lamp. The resolution of the detection system is 2 nm.
Temperature control over the sample was regulated by a THMS-600 heating stage with T95-PE temperature controller made by Linkam Scientific Instruments.

Luminescence lifetime measurements
During the luminescence lifetime measurements compounds were excited by a diode pumped 50 Hz tunable OPO laser made by EKSPLA. The luminescence emitted by the sample was collected by an optical fiber and afterwards filtered by a long pass filter (by Thorlabs, FEL500) and fed to a R2949 photomultiplier tube from Hamamatsu. Photon arrival times were categorized by the MCS6A multichannel scaler from Fast ComTec.
The data could not be fitted by a sum of simple exponential decays. For this reason stretched exponential decay was used (Eq. 1): 1 Here, and are an amplitude and lifetime of a given component i and is enclosed between 0 and 1.
The factor is introduced into the function in order to account for possibility of energy transfer towards a distribution of non-radiative centers by dipole-dipole/quadrupolequadrupole/etc. interactions. Its value is given by the type of interactions and the dimensionality of the system.
The average lifetime of the stretched exponential decay < > is calculated using the Equation 2. The procedure used for the fitting is described in 2 .
For a multiexponential decay, by variation of the lifetime one achieves compensation of the amplitude and vice versa. It is possible to obtain similar decay intensity with different values of and . In other words, and are correlated. The situation turns even more complicated, once is different from 1. The unfortunate result is that the ability to determine the precise values is greatly hindered by parameter correlation. 3 For this reason, some of the fit parameters should be considered carefully.

Total scattering measurements.
The powdered samples of 1a, 1c, 2a and 3a were loaded into 0.7 mm diameter borosilicate glass capillaries. The glass samples (1g and 3g) were mounted on top of the goniometer in vertical position.

S5
Room temperature X-ray data for samples 1a and 1c were collected at the ID22 beamline of the ESRF, Grenoble, France, at a wavelength of λ = 0.206773 Å (60 keV) using a Perkin-Elmer flat panel detector located at 38.5 cm from the sample (Qmax = 24 Å -1 ). The diffraction images were corrected and transformed to 1D diffraction patterns using the PyFAI software 1 up to Qmax = 24 Å -1 .
For the 1g, 3a and 3g samples, the data were collected using a Bruker kappaCCD diffractometer equipped with an Incoatec IµS microsource for AgKα radiation (λ = 0.5608 Å, 22.1 keV) and a CCD camera located at 10 cm from sample, which was rotated about its axis by 180° during acquisition. 36 images collected every 3° from 2-theta = 0° to 105°. The images were then integrated and averaged to yield a 1D pattern up to Qmax = 17 Å -1 . The pelletized samples were measured in reflection mode.
Sample 2a was measured up to Qmax = 17.3 Å -1 with a Bruker D8 diffractometer in Debye-Scherrer geometry equipped with MoKα1 radiation selected by a focusing primary Ge(111) monochromator and a 1D LynxEye detector with a 500µm thick Si sensor. The poorer counting statistics lead to a noisier PDF pattern as for the kappaCCD data, as visible in Fig. S5 and S36.
In all cases, data from an empty capillary were also collected for background subtraction and standard samples (LaB6, CeO2 and Ni) were used to characterize the instrumental resolution function. The reciprocal space data were converted to PDFs using the PDFgetX3 software. 2 For the laboratory data a damping correction using the Lorch function was applied prior to Fourier transform.

XAS
The sample were prepared by mixing with appropriate amounts of boron nitride (BN) and pressed in to pellet. X-ray absorption spectra were collected at the Aichi Synchrotron Radiation Center (Aichi SR in Japan) on beamline BL5S1. Au foil internal energy calibration was measured simultaneously for each sample. XAS data were background corrected and normalized using the ATHENA software. 3

XANES Simulation
The XANES spectra of 1c and 1a for all the refined models were simulated using finite difference method (FDM) in a fully relativistic frame, including thus the spin-orbit interaction, S6 as implemented in the FDMNES software. A cluster radius of 7.5 Å around the absorber was used in all calculations, seeing as simulations extended to larger radii gave identical results.

EXAFS refinement.
The Extended X-ray Absorption Fine Structure (EXAFS) regions of the spectra were analyzed via a least-square fitting of the average local structure around gold using the ARTEMIS software. 3 The theoretical paths, scattering amplitude, phase shift and mean free path of the photoelectron were calculated by the FEFF6.0 program embedded in ARTEMIS.
Additionally, a E0 parameter was refined to align the wavenumber grids of the data with those calculated by FEFF.
The number of refined parameters was limited to 9 and 11 variables for the block and chain models respectively, for a fitting range of the Fourier Transform Δk     (red)) and g-[Au(SR)]n (1g (grey), 2g (sky blue), 3g (pink)). S11 Table S1. Temperatures (in °C) of the crystallization (TC) and the decomposition (TD) of 1a, 2a and 3a obtained from TGA and DSC experiments carried out at 10°C.min -1 under air (in °C).