Synthesis of Water-Soluble Chiral DOTA Lanthanide Complexes with Predominantly Twisted Square Antiprism Isomers and Circularly Polarized Luminescence

Abstract

One-step cyclization of a tetraazamacrocycle 5 with 70% yield in a 25-gram scale was performed. Its chiral DOTA derivatives, L4, has around 93% of TSAP coordination isomer in its Eu(III) and Yb(III) complexes in aqueous solution. [GdL4] 5exhibits a high relaxivity, making it a promising and efficient MRI contrast agent. High glum values of 0.285 (J = 1) for [TbL3]and 0.241 (J = 1) for [TbL4] 5in buffer solutions were recorded.

Rapid time-resolved Circular Polarization Luminescence (CPL) emission spectroscopy

“…We have demonstrated a novel SS-CPL spectrometer, and validated it's performance and capabilities by direct comparison to a conventional SM-CPL spectrometer, which itself has been utilised in many prior peer-reviewed studies 10,21,22,24,[36][37][38][39][40][41] . The SS-CPL spectrometer is capable of unprecedented real-time fullspectra CPL spectra acquisition, in as little as 10 milliseconds by using SS spectrometer detectors.…”

“…A custom-built SM-CPL spectrometer was used as a direct comparison for the SS-CPL system. This SM-CPL spectrometer has been utilised in many prior studies 10,21,22,24,[36][37][38][39][40][41] and full technical details of its design are reported by Carr et al 33 . The emission monochromator slit width was adjusted so that the full width half maximum (FWHM) of atomic emission lines from a neon light source measured by the SM-CPL spectrometer closely matched the FWHM of the same lines measured by the SS-CPL spectrometer, ensuring that emission peak line width, line shape, and peak position were as closely matched as possible between the two CPL spectrometers.…”

“…Thus, a value of g em = 2 indicates 100% L-CPL emission, and g em = −2 indicates 100% R-CPL emission. A wide variety of CPL emitting molecular systems have been reported (see Table 1) [5][6][7][8][9][10][11][12][13][14][15][16][17][18] , with lanthanide complexes best suited to producing strong CPL emission ( g em j j up to~1.38 reported) 19 . CPL emitting molecular systems have been proposed for diverse applications, including cellular imaging 20,21 , molecular biosensing [21][22][23][24] , display technologies [25][26][27][28][29] , and as advanced security inks 30 .…”

Beyond Chiral Organic (p-Block) Chromophores for Circularly Polarized Luminescence: The Success of d-Block and f-Block Chiral Complexes

“…Finally, the selection of some (rare) inert coordination complexes followed by chiral resolution and separation may afford enantiomerically pure complexes. Inert lanthanides complexes can be obtained for polydentate ligands (i.e., cryptates, DOTA) (Gregolinski et al, 2008 ; Walton et al, 2011 ; Carr et al, 2012 ; Dai et al, 2019 ) or via the design of supramolecular assemblies, in which the lanthanide is sequestered within inert stoppers (Zare et al, 2017a ). Although the first-row transition metals are known to produce labile complexes, the preparation of inert complexes is possible with Cr III (d 3 ) or Co III (low-spin d 6 ) metals which possess large ligand-field stabilization energies, and with small and highly charged Fe III centers (Hilmes et al, 1977 ; Cantuel et al, 2004 ; Dee et al, 2019 ; Jiménez et al, 2019 ).…”

“…The introduction of chiral substituents into the cyclen ring and/or into the pendant arms of the DOTA derivative drives the formation of one stereoisomer over the others (Dickins et al, 1997 , 1999 ; Ranganathan et al, 2002 ; Woods et al, 2003 ). This is of crucial importance for controlling the degree of local helicity and the associated dissymmetry factor (Carr et al, 2012 ; Dai et al, 2019 ). These complexes have been widely used as CPL probes for sensing small molecules and proteins thanks to the great sensitivity of the CPL signals of Tb 3+ , Eu 3+ , Dy 3+ , Yb 3+ , and Nd 3+ to conformational and structural modifications (Beeby et al, 2000 ).…”