铕配合物中CPL检测方案(圆二色光谱仪)

Application Note High-resolution CPL spectrum measurement of2/3Application Notea europium complex CDDSSpectroscopy High-resolution CPL spectrum measurement of aeuropium complex [Eu(facam)] When chiral compounds are excited with unpolarized light，the difference in emission intensities of left- and right-handed circularly polarized light can be measured. Thisphenomenon is called circularly polarized luminescence(CPL). While circular dichroism provides information aboutthe ground state of chiral molecules， CPL spectroscopyprobes the excited states of chiral molecules. In recent years， CPL-active molecules have been usedfor a wide range of technical applications such as securityencoding， bioanalytical probes， and liquid crystal displaydevices. Chiral lanthanide complexes are one example oftarget molecules for CPL measurements. These complexesare known to exhibit sharp emission bands and require anarrow bandwidth during CPL measurements. JASCO has recently developed a high sensitivity CPLspectrometer. By combining CPL with ECD， more structuralinformation regarding chiral molecules can be obtained.To measure sharp CPL peaks at a high resolution， JASCO'sCPL-300 spectrometer uses two prism monochromators.Both the emission and excitation monochromators areequipped with continuously variable slit drives， which allowfor an appropriate wavelength and band width selection. This application note demonstrates the high resolution CPLspectrum measurements of europium tris[3-(trifluoromethylhydroxymethylene)-(+)-camphorate](Eu(facam)3) using aCPL-300.Eu(facam)， is a common NMR shift reagent and hasbeen used as a standard for CPL measurements.2 Keywords JASCO INC. 28600 Mary’s Court， Easton， MD 21601 USA Experimental 5.5 mM Eu(facam) was prepared in DMSO. Excitation wavelength 373 nm Excitation slit width 4000 um Emission bandwidth 3nm Scan speed 200 nm/min Response time 4 sec Data acquisition interval 0.1nm Accumulations 4 Path length 10 mm The absorption spectrum of Eu(facam)/DMSO solution was measured using a V-760 spectrometer and a 0.1 mmpathlength cylindrical cell and holder. The fluorescence spectra were obtained using a FP-8300 spectrofluorimeter and a10x10 mm pathlength rectangular cell. Results In order to find the excitation maximum needed to obtain the CPL and fluorescence emission spectrum of Eu(facam)3/DMSO， the absorption spectrum was first obtained. Figure 1 depicts a maximum absorption peak (blue) at 309 nm.However， in order to optimize the excitation wavelength used in the CPL and fluorescence measurements， an excitationspectrum was subsequentially measured at the expected emission maximum peak's wavelength at 613 nm. The excitationspectrum shows an apparent maximum at 373 nm (Figure 1， red). The excitation wavelength was set to 373 nm and theCPL and fluorescence measurements of Eu(facam)3/DMSO were measured and are shown in Figure 2. Figure 1. The absorption (blue)， excitation (red) and emission (green) spectra of Eu(facam)/DMSO solution. 28600 Mary's Court， Easton， MD 21601 USA Figure 2. The glum (top)， CPL (middle)， and fluorescence (bottom) spectra of Eu(facam)./DMSO solution. All three spectra in Figure 2 show the 5D。 --> 7F， magnetic-dipole transition band at 595 nm. The additional emission bandat 611 nm is due to the 5D， -->7F， electronic-dipole transition.3The CPL spectrum shows strong signals which confirms thepresence of the chiral facam ligands. The degree of CPL can be described by g um， the luminescent dissymmetry factor.This value quantifies the asymmetric environment surrounding the complexes’metal ions. The larger the dissymmetryfactor， the more polarized the emitted light will be. A g of ±2 indicates the complete polarization of light while 0correlates to unpolarized emitted light. Figure 2 (top) shows a gum value ca. -0.8 for the 595 nm transition band， indicatinga chiral species is present. Conclusion The JASCO CPL-300 spectrometer can perform CPL measurements that produce high resolution spectra. The CPL，fluorescence， and g spectra are all consistent with the literature.24.5 References 1. F Zinna and L Di Bari， Chirality， 2015， 27：1. 2. HG Brittain and FS Richardson， JACS， 1976，98： 5858 3. JP Riehl， Chemical Reviews， 1986， 86： 1. 4. CK Luk and FS Richardson， JACS，1975，97：6666. 5. T Harada，Y Nakano， M Fujiki， M Naito， T Kawai， and Y Hasegawa， Inorganic Chemistry， 2009， 48： 11242. Tel： ( Fax： ( pplication Library： http：//www.jascoinc.com/applications This application note demonstrates the high resolution CPL  spectrum measurements of europium tris[3-(trifluorometh ylhydroxymethylene)-(+)-camphorate] (Eu(facam)3) using a  CPL-300. Eu(facam)3 is a common NMR shift reagent and has  been used as a standard for CPL measurements.2