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89Zr−immunoPET is a hot topic as 89Zr cumulates the advantages of 64Cu and 124I without their drawbacks. We report the synthesis of a model ligand of a chiral bioconjugable tetrahydroxamic chelator combining the desferriferrioxamine B siderophore and 1‐hydroxy‐2‐piperidone ((PIPO)H), a chiral cyclic hydroxamic acid derivative, and the study by NMR spectroscopy of its zirconium complex. Nuclear Overhauser effect measurements (ROESY) indicated that the complex exists in the form of two diastereomers, in 77 : 23 ratio, resulting from the combination of the central chiralities at the 3‐C of the (PIPO)H component and at the Zr4+ cation. The 44 lowest energy structures out of more than 1000 configurations/conformations returned by calculations based on density functional theory were examined. Comparison of the ROESY data and the calculated interatomic H⋅⋅⋅H distances allowed us to select the most probable configuration and conformations of the major complex. [ABSTRACT FROM AUTHOR]

A series of tetraaza‐expanded calix[4]arene analogues (2–4), in which two of the four aryl groups are ethylene‐protected thiophenol components were prepared from tetraaldehyde 1. Two of these strapped macrocycles were characterized crystallographically, as well as the dipalladium complex of 4. The same tetraaldehyde had been previously used for the synthesis of a macrotricycle (5) and a macropentacycle (6), the coordination properties of which have been investigated. In particular, ligand 6 was shown to be able to encapsulate a Cu+ or a Ag+ ion in the tetrahedral coordination pocket offered by a bridgehead nitrogen atom and the three proximal thioether sulfur atoms. [ABSTRACT FROM AUTHOR]

A sterically encumbered [[N.sub.2][S.sub.6]] macropentacycle related to diazamacrobicycles and cryptands is prepared by the [1!] condensation reaction between functionalized macrocyclic and macrotricyclic precursors. Adoption of the in, out form by macropentacycle in the crystal and in solution at low-temperature has resulted from the steric crowding and strain introduced by the [15]ane-[N.sub.2][S.sub.2] macrocyclic bridging subunits.

Research has been conducted on the electron transfer reactions. The hypothesis coordination of the metal cations can enhance electron transfer rates and the role of the space jumps versus metal-ligand bonds in the electron transfer pathway have been investigated and the details are reported.

A bis-chelating ligand is made of two 1,10-phenanthroline subunits using Skraup synthesis. In addition fluorescence spectroscopy measurements have demonstrated that Ru(II) complexes retains the luminophore properties of Ru(II) tris-chelate analogues.

A dicopper(I)-complexed (3)-rotaxane was produced in 34% yield by a transition-metal-templated technique involving a bis-chelating molecular thread, macrocycles incorporating the complementary chelating unit, and porphyrin stoppers are primary components. A tetracopper(I)-complexed (5)-rotaxane was obtained as a byproduct in 8% yield. Coordination chemistry was conducted either at the 2,9-diphenyl-1,10-phenanthroline chelates or at the porphyrin stoppers.

Chiral gold(I) acetylide trinuclear complexes 1–3 based on the cyclotribenzylene platform and terminal PR3 ligands (R=Ph, Et, and Cy, respectively), were characterized and their light emission studied. They exhibited long‐lived blue phosphorescence in CHCl3 and a weak fluorescence in the UV. In MeOH/CHCl3 mixtures of >1:1 volume ratio, 1 and 2 exhibited a new emission band at ca. 540 nm that developed at the expense of the UV emission. DLS studies demonstrated the presence of molecular aggregates of Ø 30–80 nm. The green emission observed in MeOH‐rich solvent mixtures was therefore induced by aggregation, and could originate from Au⋅⋅⋅Au interactions. The AIE spectrum of 3 was observed only in solutions containing 99 % of MeOH, and correlated with its solid state emission. The AIE profiles of the enantiomers of 1 differed from that of rac‐1, suggesting that the latter is a true racemate. [ABSTRACT FROM AUTHOR]

Chemical topology is an interesting field with topics that can easily be demonstrated in the chemistry classroom. The basic premise of chemical topology assumes that chemical bonds are totally flexible and can stretch, flatten or bend but not break. Using this premise, molecules can be represented in many ways and molecules that are otherwise unsimilar can have identical topologies. Some examples and classroom demonstrations are presented.

Covalently-linked multicomponent systems use bidentate bpy-type and terdentate tpy-type ligands to produce photo-induced charge separation through the formation of Ru(II) and Os(II) metal complexes which serve as photo sensitizers. Two terpyridine units can be linked to produce rod-like bridging bis-tpy ligands which can be used for energy transfer of different metals. The redox agent, ferrocene, is not the right electron donor in photoexcited supramolecular systems as the low-lying excited state of Fc is Mc in nature and produce distorted luminescence.

A general precursor to rotaxane-type structures results from the transition metal-directed threading of a molecular fragment having a central chelate and an end-attached gold(III) porphyrin into a presynthesized coordinating ring. A copper(I)-complexed (2)-rotaxane and a new compartmental (3)-rotaxane result from the design of the second porphyrin's functioning as a good stopper, following threading.

The electron-transfer method between zinc(II) and gold(III) porphyrinic subunits reveals the involvement of the spacer moiety as an intermediate. The speed of electron transfer is influenced by the structure of the molecule, and varies in rotaxanes. The spacer group is likely to turn when the temperature is high. The speed of electron transfer and the energy gap are inversely connected in the electron-transfer reactions. The actual intermediate in the reactions is not the spacer moiety but the reduced central zinc(II) complex.

Experimental findings were elicited from a bis(porphyrin) associated with copper(I) bis-(1,10-phenanthroline), developed by limiting the accessory 1,10-phenanthroline ligand in a 30-membered macrocyclic ring, and formed a rotaxane (3) where the porphyrin subunits function as stoppers. The rates of photoinduced electron transfer in compounds 1-3, when compared, hint that the copper (I) complex increased the rate of forward electron transfer as a result of a superexchange process. Quick electron transfer to the appended gold porphyrin from the zinc porphyrin results when any one porphyrin is preferentially activated.

The preparation and characterization of copper(I) catenates and metal-free analogues in optically active media are presented. Copper(I) (2)-catenates are generated via a three-dimensional template synthesis. 1H NMR spectroscopy shows these complexes to be topologically chiral, with the splitting of the signals of the aromatic protons enantiotopic by external comparison. On the other, the splitting observed from the achiral Cu(I) catenate with only a single oriented ring, is enantiotopic by internal comparison.

Study reports in detail the proporties of the proton complex of macropentacycle, correlations between the structures in the solid state and in solution, slow kinetics of formation, induction of the sense of chirality by optically active 1,1'-binaphthyl-2,2'-diyl phosphate anion.

Purpose: Currently, the most commonly used chelator for labelling antibodies with 89Zr for immunoPET is desferrioxamine B (DFO). However, preclinical studies have shown that the limited in vivo stability of the 89Zr-DFO complex results in release of 89Zr, which accumulates in mineral bone. Here we report a novel chelator DFOcyclo*, a preorganized extended DFO derivative that enables octacoordination of the 89Zr radiometal. The aim was to compare the in vitro and in vivo stability of [89Zr]Zr-DFOcyclo*, [89Zr]Zr-DFO* and [89Zr]Zr-DFO. Methods: The stability of 89Zr-labelled chelators alone and after conjugation to trastuzumab was evaluated in human plasma and PBS, and in the presence of excess EDTA or DFO. The immunoreactive fraction, IC50, and internalization rate of the conjugates were evaluated using HER2-expressing SKOV-3 cells. The in vivo distribution was investigated in mice with subcutaneous HER2+ SKOV-3 or HER2− MDA-MB-231 xenografts by PET/CT imaging and quantitative ex vivo tissue analyses 7 days after injection. Results: 89Zr-labelled DFO, DFO* and DFOcyclo* were stable in human plasma for up to 7 days. In competition with EDTA, DFO* and DFOcyclo* showed higher stability than DFO. In competition with excess DFO, DFOcyclo*-trastuzumab was significantly more stable than the corresponding DFO and DFO* conjugates (p < 0.001). Cell binding and internalization were similar for the three conjugates. In in vivo studies, HER2+ SKOV-3 tumour-bearing mice showed significantly lower bone uptake (p < 0.001) 168 h after injection with [89Zr]Zr-DFOcyclo*-trastuzumab (femur 1.5 ± 0.3%ID/g, knee 2.1 ± 0.4%ID/g) or [89Zr]Zr-DFO*-trastuzumab (femur 2.0 ± 0.3%ID/g, knee 2.68 ± 0.4%ID/g) than after injection with [89Zr]Zr-DFO-trastuzumab (femur 4.5 ± 0.6%ID/g, knee 7.8 ± 0.6%ID/g). Blood levels, tumour uptake and uptake in other organs were not significantly different at 168 h after injection. HER2− MDA-MB-231 tumour-bearing mice showed significantly lower tumour uptake (p < 0.001) after injection with [89Zr]Zr-DFOcyclo*-trastuzumab (16.2 ± 10.1%ID/g) and [89Zr]Zr-DFO-trastuzumab (19.6 ± 3.2%ID/g) than HER2+ SKOV-3 tumour-bearing mice (72.1 ± 14.6%ID/g and 93.1 ± 20.9%ID/g, respectively), while bone uptake was similar. Conclusion: 89Zr-labelled DFOcyclo* and DFOcyclo*-trastuzumab showed higher in vitro and in vivo stability than the current commonly used 89Zr-DFO-trastuzumab. DFOcyclo* is a promising candidate to become the new clinically used standard chelator for 89Zr immunoPET. [ABSTRACT FROM AUTHOR]