Thermo nicolet nexus 470 ftir

Details of the synthesis of F, M, 1-exo, 1-endo, photographs of samples, spectroscopic investigations are provided in Supplementary Information. 10,12-Pentacosadiynoic acid (PCDA) was obtained from GFS Chemicals (Powell, OH). Furfuryl alcohol and N-(4-hydroxy phenyl) maleimide were purchased from Sigma-Aldrich (Korea). Raman spectra were recorded on a LabRAM HR Evolution Raman spectrometer (Horiba Scientific, 785 nm laser source). UV absorption and transmittance spectra were recorded on a single beam Agilent 8453 UV−Vis spectrometer (Agilent Technologies, Waldbronn, Germany). IR spectra were recorded on a Thermo Nicolet NEXUS 470 FTIR using an ATR accessory (Thermo Fisher Scientific, Inc.). ¹H and ¹³C NMR spectra were recorded on a Varian Unitylnova (600 MHz) spectrometer at 298 K in CDCl₃. High-resolution mass spectra (HRMS) were recorded on an SYNAPT G2 (water, UK) using a time-of-flight (TOF) analyzer.

Absorption spectra were obtained by using UV-Vis Agilent 8453 diode-array spectrophotometer (Santa Clara, CA, USA). Chemical structure study was made by using Thermo Nicolet Nexus-470 FTIR (Fourier-transform infrared spectroscopy) spectrophotometer (Thermo Fisher Scientific, Waltham, MA, USA) with a diamond ATR adapter. Fluorescence characteristic, fluorescence quantum yield and pH-dependence fluorescence study at pH = 4, 5, 6, 7, 8 and 9 were made by FP-750 Jasco Spectrofluorometer (JASCO, Tokio, Japan). For the fluorescence studies, the CQDs solutions were diluted so their absorbance was A = 0.05. During pH-dependence studies the samples were at 365 nm. Buffer solutions were prepared by using the CX-551 Elmetron pH-meter. The fluorescence quantum yield of CQDs was measured by using a comparative method with quinine sulfate (Sigma-Aldrich, Poznań, Poland) in 0.1 M sulfuric acid (Sigma-Aldrich, Poznań, Poland) as a standard (fluorescence quantum yield (QY) = 0.54) by the method described in the previous article [28 (link)]. The QY was calculated using the following Equation (1): ${\mathrm{QY}}_{\mathrm{s}}={\mathrm{Q}}_{\mathrm{r}}\left(\frac{{\mathrm{A}}_{\mathrm{r}}}{{\mathrm{A}}_{\mathrm{s}}}\right)\left(\frac{{\mathrm{E}}_{\mathrm{s}}}{{\mathrm{E}}_{\mathrm{r}}}\right){\left(\frac{{\mathsf{\eta }}_{\mathrm{s}}}{{\mathsf{\eta }}_{\mathrm{r}}}\right)}^2$
QY = Fluorescence quantum yield;
η = Refractive index of the solvent;
A = Absorbance of the solution;
E = Integrated fluorescence intensity of the emitted light.
Subscripts ‘r’ and ‘s’ refer to the quinine sulfate (reference) and evaluated sample respectively.