Pyrene‐Functionalised Copper Complexes as Potential Dual‐Modality Imaging Agents

Abstract

The syntheses of pyrene‐functionalised bis(thiosemicarbazonato)zinc and ‐copper complexes are reported. In contrast to previously reported bis(thiosemicarbazonato)Cu2+ complexes which are nonfluorescent, the pyrene group remains highly fluorescent. The compounds have been characterised by using a wide range of techniques including reverse‐phase HPLC, cyclic voltammetry, NMR, electronic absorption (UV/Vis), infrared and fluorescence emission spectroscopy. Spectroelectrochemistry experiments demonstrated that the Cu2+ complexes undergo quasi‐reversible one‐electron reduction at biologically accessible potentials. Density functional theory calculations were used to probe the electronic structure of the pyrene‐functionalised copper complexes and confirmed that the ligand‐based fluorescent emission occurs due to the absence of orbital interactions between the pyrene and bis(thiosemicarbazonato)copper groups. These preliminary studies demonstrate that the new copper complexes have potential to be used as dual‐modality agents for in vitro cellular fluorescence microscopy and in vivo positron emission tomography experiments.

Fluorescent Copper(II) Complexes of Asymmetric Bis(Thiosemicarbazone)s: Electrochemistry, Cellular Uptake and Antiproliferative Activity

“…This can be attributed to the separation of excited states of copper(II) and the ligand via distortion in the geometry of the complex in the excited state [49,50] . Similar observations were noted by Holland and coworkers on pyrene functionalized bis(thiosemicarbazonato) copper(II) complexes and explained on the basis of single photon emission experiments combined with the density functional theoretical calculations [76] …”

Synthesis of Thicolchicine‐Based Conjugates: Investigation towards Bivalent Tubulin/Microtubules Binders

“…The synthesis of conjugate compounds bearing a longer pseudo‐peptidic linker was considered (Scheme ). To this extent, the 10 carbon atoms chain of compound 3 was furtherly elongated, through the introduction of the tert ‐butyl 2‐aminoethylcarbamate fragment 5 , obtained according to reported procedure . The cleavage of the Boc protecting group, upon treatment with TFA led to compound 7 .…”

“…To this extent, the 10 carbon atoms chain of compound 3 was furtherly elongated, through the introduction of the tert-butyl 2-aminoethylcarbamate fragment 5, obtained according to reported procedure. [15] The cleavage of the Boc protecting group, upon treatment with TFA led to compound 7. The obtained free amino group was exploited for a further reaction with sebacic acid.…”

CuII-selective bispidine–dye conjugates

“…This bispidol 3 might be used for dye-coupling with isocyanate groups and was transformed to the corresponding amine B1 by a Mitsunobu reaction, using diphenyl phosphoryl azide and an in situ-Staudinger reaction of the organo azide (method A, Scheme 1) [21]. In method B, the piperidone 1 was reacted in a double Mannich reaction with formaldehyde and mono-Boc-ethylendiamine 4 [22] to the bispidone 5. Diastereoselective reduction of the carbonyl at C 9 with sodium borohydride, following the cleavage of the Boc-protection group [23], afforded the free amine B1 in moderate yields.…”