Oxford diffractometer

CIF table, selected bond lengths and bond angles of the Cu²⁺–L complex are given in Tables 2, S1 and S2,† respectively. Single-crystal X-ray data were collected using a Rigaku Oxford diffractometer with graphite-monochromated Cu-Kα (λ = 1.54178 Å) radiation at 110(2) K. The “Bruker Saint Plus” program³⁹ was used for data reduction. Data were corrected for Lorentz and polarization effects; an empirical absorption correction (SADABS) was applied.³⁹ The structure was solved by direct methods with SIR-97 and refined by full-matrix least squares methods based on F² by using SHELXL-97,^{40 (link)} incorporated in the WinGX 2014.1 crystallographic package.^{41 (link)} All nonhydrogen atoms were refined with anisotropic thermal parameters. The positions of the hydrogen atoms were calculated assuming ideal geometries, but were not refined.

Slow evaporation in a variety of commonly used solvents (ranging from apolar to polar aprotic and polar protic) was employed for polymorph screening for all eight compounds,³⁶ and high-quality single crystals were used for structure determination by SCXRD. The identity of individual batches of crystals was determined by PXRD.
The crystallographic data of all crystal forms were collected on a Rigaku Oxford diffractometer at ambient temperatures, except for 1-I, for which data collection was carried out on a Bruker APEX-II diffractometer with a CuKα radiation (λ = 1.54184 Å). Cell refinement and data reduction were performed using CrysAlisPro. Structure solution and refinement were carried out using the SHELXT³⁷ and SHELXL^{38 (link)} programs, respectively. PXRD data for the crystal forms were collected on a Rigaku X-ray diffractometer with CuKα radiation (40 kV, 15 mA, λ = 1.5406 Å) between 5.0 and 50.0° (2θ) at ambient temperatures.
DSC experiments were performed on SII instruments DSC6220 (Seiko Instruments Inc., Japan). TGA experiments were run on SDT Q600 (TA Instruments, USA). Tzero® pans and aluminum hermetic lids were used for measuring a few milligrams of a finely ground sample, at a heating rate of 10 °C min⁻¹.

All solvents (analytical grade and spectroscopic grade) were obtained from Finar (India) and Spectrochem (India) and the solvents were purified using standard literature methods. Deuterated solvents for NMR were bought from Sigma-Aldrich (India) and used as received. All metal salts and other chemicals were obtained from Alfa-Aesar (India), Spectrochem (India) and Merck (India). Melting points were measured using a BUCHI M-500 instrument. Fourier transform infrared (FT-IR) spectra were recorded on a BRUKER ALPHA-T FT-IR spectrometer using KBr pellets. A PerkinElmer model Lambda 650 UV-vis spectrophotometer was used for recording the absorption spectra. Emission spectra were recorded on a Fluoromax 4P Spectro-fluorometer (Horiba-Jobin-Mayer, Edison, NJ, USA). The bioimaging experiments were carried out using a Leica TCS SP5 confocal microscope and the fluorescence lifetime was measured using a time-correlated single-photon counting (TCSPC) spectrometer (Edinburgh, OB920) instrument. ¹H and ¹³C NMR spectra were recorded on a Bruker AVANCE 400 NMR spectrometer. A Bruker microTOF-Q II mass spectrometer was used for electrospray ionization mass spectrometry (ESI-MS) analysis of the compounds. X-ray data were collected using a Rigaku Oxford diffractometer with graphite-monochromated Cu-Kα (λ = 1.54178 Å) radiation at 110(2) K.