Michel Holler's research while affiliated with University of Strasbourg and other places

... Each isomeric bis-addition pattern displayed a typical absorption feature in the visible light region, almost independent of the type of addends and the substituents [50]. Regarding the structural assignment of 24, the UV-Vis spectrum is in accordance with that of a trans-3 bisadduct (see Supplementary Materials), which usually is the preferred regioisomer in the case of hetero functionalization with sterically demanding addends [50][51][52]. However, a further confirmation of this data through NMR experiments was hampered due to the broad 1H and 13C signals generated by the presence of rotamers. ...

... 17−25 Recently, stereodefined C 60 [3:3] hexa-adducts were prepared by two subsequent click reactions. 26 For the controlled assembly, a C 60 tris-adduct was first regioselectively prepared using a macrocyclic malonate, which was then exposed to a Bingel cyclopropanation with another malonate. ...

... Following their discovery in 2008 [2], they became rapidly important building blocks in the field of supramolecular chemistry owing to their easy preparation [1]. On the other hand, the presence of their ten peripheral substituents makes pillar [5]arenes attractive compact scaffolds for the design of multifunctional nanomaterials [3]. The most efficient strategy for the preparation of such compounds is based on the ten-fold post-functionalization of easily affordable pillar [5]arene building blocks. ...

... [10] As part of this research, our group became recently interested in the preparation of versatile pillar [5]arenecontaining rotaxane building blocks equipped with activated stoppers allowing the synthesis of a large variety of derivatives by stopper exchange reactions. [11][12][13] As these chemical transformations occurred by either an addition/elimination mechanism or a concerted nucleophilic substitution, no intermediate allows for the disassembly of the interlocked molecular ensemble and the rotaxane structure is fully preserved during the stopper exchange reactions. In this paper, we now report on a stepwise functionalization of a symmetrical pillar [5]arenebased building block. ...

... Differently, most of the published dinuclear copper complexes show two separated coordinated copper units, each with its own LUMO level, communicating through a bridge unit, e. g. amine based ligand [11a,16] or phosphine based ligand. [19,17,20] The stability of all complexes in dichloromethane, as already verified by 1 H-NMR spectra, was checked with absorbance spectra recorded at different times. The absorbance spectra of all complexes do not show any change after a week and they do not show any new peak (Figures S3.5-S3.8), ...

... The UV-visible spectra of Fig. 10a) for Cu(NO 3 ) 2 present the same characteristics as the previous ones, indicating the ligand-centered region with intraligand π→π* transitions at low wavelengths (200-400 nm). The results showed that nitrates have a strong binding affinity, showing at 750 nm a characteristic high absorbance attributed to a metal-ligand charge transfer transition (MLCT) with d→d* transitions [26][27][28] with a signal response in the region of 400-500 nm, attributable to the presence of stable Cu + in the electrolyte. The signals in the UV spectrum at wavelengths from 600 to 900 nm indicate changes in the charge transfer from metal to ligand, while at 450 nm after the LC region, there is an increase in absorbance as a function of the reduction of Cu 2+ species. ...

... Mechanochemical solvent-free conditions have been successfully used to prepare rotaxanes. [15][16][17] Our group has shown that such conditions are particularly well suited to obtain pillar[5]arene-containing rotaxanes in good yields. [16] Indeed, the association between the axle reagent and the pillar[5]arene leading to rotaxane formation is favored in the solid state. ...

... The usage of chelating phosphines instead of monodentate triphenylphosphine was motivated by significant exciplex quenching for [Cu(PPh 3 ) 2 (NN)] + complexes (NN for example being 1,10-phenanthroline or 2,9-dimethyl-1,10-phenanthroline) in methanol [15,16] and a hard control of the speciation, that is, the coordination of the counter anion or formation of the homoleptic complexes. [15][16][17][18][19] It was observed that coordination chemistry and excited state properties depend on the interplay of steric and electronic ligand properties. For instance [Cu(PPh 3 ) 2 (2,9-dimethylphenanthroline)] + is more prone to undergo PPh 3 ligand dissociation than [Cu-(PPh 3 ) 2 (phenanthroline)] + due to inter-ligand steric repulsion but exhibits appreciable emission from a charge transfer state as a result of the crowded coordination sphere (avoidance of exciplex quenching). ...

... 14 The presence of intramolecular π-stacking interactions between arene rings is beneficial to the PLQY values of the complexes. 6,15 For improved chemical stability and beneficial photophysical properties, the stabilization of the tetrahedral coordination geometry of the copper(I) centre is an essential feature in [Cu(P^P)(N^N)] + species. 6,16,17 When such compounds are employed in the emitting layers of LEC devices, the use of small alkyl substituents such as methyl and ethyl in the 6-or 6,6′-positions of the bpy ligand backbone enhance LEC performances. ...

... In contrast to the frequent reports of rim-functionalized pillar[n]arenes, there have only been a handful of reports of functionalization at the aromatic ring, [23][24][25][26][27] or belt positions (also described as the "lateral" positions). [28][29][30] Notably, introduction of functional groups at the methylene carbon atoms induces chirality in the pillar [n]arenes and in the case of functionalization at multiple belt positions results in mixtures of configurational isomers (arising from the fact that each belt-substituent can be cis or trans to the adjacent substituent). The reported belt functionalizations have all involved P5 and have either involved initial bromination or lithiation of the belt CH2 groups. ...