Role of the Antenna in Tissue Selective Probes Built of Lanthanide−Organic Chelates

Abstract

The role of the antenna in the process of the host sensitized luminescence of the DOTA cage coordinated with the Eu ion is investigated. The analysis of the optimal geometries of DOTA modified by several antennas is based on the results of density functional theory (DFT) calculations. The physical environment of the luminescence center (the lanthanide ion) is illustrated by charge density maps and described by the values of the crystal field parameters directly evaluated. The conclusions derived from this theoretical analysis support earlier observations that antennas attached to the cage play the sole role of harvesting and transferring the energy to the lanthanide ion, whereas the cage perturbs the symmetry of the environment of the lanthanide ion, giving rise to the sensitized luminescence. The implications of the separation of the two parts of the organic chelate, cage and antenna, are discussed within the theoretical models of the energy transfer and of forced f <--> f electric dipole transitions.

Applications of Density Functional Theory (DFT) to Investigate the Structural, Spectroscopic and Magnetic Properties of Lanthanide(III) Complexes

“…Hess and co. [186] performed DFT calculations (B3LYP, large-core RECP) on Eu III complexes with DOTA and DO3A-substituted ligands containing different pendant arms. Subsequently, the physical environment of the metal ion was investigated by calculating charge density maps that were translated into the numerical values of the crystal field parameters that define the crystal field potential influencing the lanthanide ion.…”

“…Theoretical investigations performed on DOTA-like complexes based on molecular mechanics [179][180][181][182][183], Hartree-Fock [184,185], density-functional theory [186,187], or classical molecular dynamics [188,189], have been reported in the literature. These investigations contributed to increase the understanding of the structure and dynamics of this important family of complexes.…”

Luminescence Resonance Energy Transfer in Heterodinuclear LnIII Complexes for Sensing Biologically Relevant Anions

“…Generally, chromophores are incorporated into the multidentate ligand to act as an antenna for harvesting photons and transferring them to the Ln III ion by resonance energy transfer (RET). [5][6][7][8][9][10] Many probes based on such sensitized excitation of the Ln III ions have been applied to specific biochemical anions such as those shown in the work by Parker [11][12][13][14][15][16][17][18] and others. [19][20][21][22][23][24][25][26][27] [a] Department, Institution, Department of Chemistry, University (2) have internuclear distances of 7.8 Ϯ 0.6 and 8.0 Ϯ 0.7 Å, respectively.…”

Efficiency of the energy transfer in lanthanide-organic chelates; spectral overlap integral

“…The theoretical description of the energy transfer have begun with the classical papers of Förster [5] and Dexter [6][7][8][9] and was developed by Kushida [10][11][12], Malta [13][14][15][16][17] and Smentek [18][19][20][21][22][23][24].…”