A metal-directed self-assembled electroactive cage with bis(pyrrolo)tetrathiafulvalene (BPTTF) side walls.

A straightforward synthesis of a bis(pyrrolo)tetrathiafulvalene (BPTTF)-based tetratopic ligand bearing four pyridyl units is described. The first example of a TTF-based self-assembled cage has been produced from this redox-active ligand through metal-directed synthesis with a cis-coordinated square-planar Pt(II) complex. The resulting cage corresponds to a trigonal-prismatic structure, as shown by X-ray crystallography. A UV-vis titration indicated that the electron-rich cavity can be used to incorporate one molecule of tetrafluorotetracyano-p-quinodimethane (TCNQF(4)).

A BPTTF-based self-assembled electron-donating triangle capable of C60 binding.

A kinetically stable self-assembled redox-active triangle is isolated. The resulting electron-donating cavity, which incorporates three BPTTF units, exhibits a remarkable binding ability for electron-deficient C(60), supported by a favorable combination of structural and electronic features.

Exclusive self-assembly of a polar dimeric capsule between tetraurea calix[4]pyrrole and tetraurea calix[4]arene.

The exclusive self-sorting observed in the self-assembly process between tetraurea benzyl calix[4]pyrroles and tetraurea tolyl calix[4]arene to afford unprecedented hybrid dimeric capsules with polar interiors is described. The coencapsulation of a solvent molecule with an organic guest yields four particle aggregates in which the guests are confined and restricted into single hemispheres due to the polar requirements of the internal cavity.

Efficient self-sorting of a racemic tetra-urea calix[4]pyrrole into a single heterodimeric capsule.

A racemic calix[4]pyrrole self-sorts into a single achiral heterodimeric capsule. This process is induced either by encapsulation of one ditopic or two monotopic N-oxide guests. The influence of the guest structure in the dynamics of the disproportionation process of the two homochiral capsules is reported. The unidirectional sense of rotation of the urea groups assigned to the heterodimeric capsule is explained as the outcome of an induction of chirality from the stereogenic centers.

Selective pairwise encapsulation using directional interactions.

Trimethylamine N-oxide and trimethylphosphine oxide guests are pairwise encapsulated in a dimeric capsule self-assembled from a tetraurea aryl extended calix[4]pyrrole. The capsule possesses polar functional groups in its interior capable of controlling the orientation of the included guests. A modest selectivity is observed during the encapsulation process that is beyond the controls of size or shape exclusion.

N-aryl pyrrolo-tetrathiafulvalene based ligands: synthesis and metal coordination.

A straightforward general synthetic access to N-aryl-1,3-dithiolo[4,5-c]pyrrole-2-thione derivatives 6 from acetylenedicarbaldehyde monoacetal is depicted. In addition to their potentiality as precursors to dithioalkyl-pyrrole derivatives, thiones 6 are key building blocks to N-aryl monopyrrolo-tetrathiafulvalene (MPTTF) derivatives 10. X-ray structures of four of these thiones intermediates, reminiscent of the corresponding MPTTF derivatives, are provided. When the aryl group is a binding pyridyl unit, the MPTTF derivative 10a can coordinate M(II) salts (M = Pt, Pd). The first examples of metal-directed orthogonal MPTTF-based dimers 11-14, obtained through coordination of 10a to cis-blocked square planar Pt or Pd complexes are described. Studies on the parameters influencing the dimer construction are presented, as well as first recognition properties of the resulting electron-rich clip for C(60).

Selective monosulfoxidation of tetrathiafulvalenes into chiral TTF-sulfoxides.

Four inner tetrathiafulvalene-sulfoxides have been synthesized upon reaction of tetrathiafulvalene (TTF), tetramethyl-tetrathiafulvalene (TMTTF), tetrakis (thiomethyl)-tetrathiafulvalene (TMT-TTF), and bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) with enantiopure (+) or (-)-(8,8-dichlorocamphorylsulfonyl)-oxaziridine as oxidizing agent. Chiral HPLC studies indicate very weak enantioselectivities for TTF-SO 3 and TMTTF-SO 4, formation of racemic mixture in the case of TMT-TTF-SO 5, and a rather good selectivity, up to 44% ee, in the case of BEDT-TTF-SO 1. The solid state structures of TMTTF-SO 4 and TMT-TTF-SO 5 have been determined by single crystal X-ray diffraction. Both compounds crystallize as racemates in the centrosymmetric triclinic space group P-1. Theoretical calculations at DFT/B3LYP/6-31+G* level afford optimized geometries in good accordance with the experimental structures and emphasize the participation of the chiral sulfoxide group in HOMO and LUMO. Time-dependent DFT calculations corroborated with electronic circular dichroism spectra allow the assignment of the absolute configuration (R) for the major enantiomer of 1 when the (+)-sulfonyl-oxaziridine is used as oxygen transfer reagent. Preliminary semipreparative HPLC separation provided enantioenriched fractions up to 63% ee.

Stereoselective self-assembly of atropoisomeric Pd(II) metallocycles induced by an aromatic guest.

A new dinuclear Pd(II) metallocycle consisting of a 4,4'-bipyridin-1-ium ligand with a quinoline moiety was self-assembled in aqueous solution with the aid of template molecules; the situation found in solution in which both syn and anti or only the anti atropoisomers are observed strongly relies on the intermolecular host-guest interactions.

Self-assembly of 1:2 inclusion complexes between a metallocycle host and dihydroxyaromatic guests: a redox controlled complexation process.

Two new 1:2 inclusion complexes were prepared by self-assembly of three components: a ligand based on 4,4'-bipyridinium, a square-planar Pd complex, and a dihydroxyaromatic guest (hydroquinone or 1,5-dihydroxynaphthalene) in a 2:2:2 ratio. Their X-ray structural analyses revealed that the complexes are stabilized by pi-pi stacking and [C-H...pi] interactions.

Chemo- and enantioselective sulfoxidation of bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) into chiral BEDT-TTF-sulfoxide.

Selective sulfoxidation of BEDT-TTF (bis(ethylenedithio)-tetrathiafulvalene) with enantiopure (camphoryl-sulfonyl)oxaziridine derivatives provided the inner monosulfoxide, as demonstrated using single crystal X-ray analysis, with an enantiomeric excess of 44% (up to 74% after recrystallization).

Molecular catenation via metal-directed self-assembly and pi-donor/pi-acceptor interactions: efficient one-pot synthesis, characterization, and crystal structures of [3]catenanes based on Pd or Pt dinuclear metallocycles.

Dinuclear square metallocycles 3a,b assemble spontaneously when M(en)(OTf)2 (M = Pd, Pt) and a 4,4'-bipyridinium ligand are mixed in acetonitrile. Six new [3]catenanes were prepared in good yields by thermodynamically driven self-assembly reaction of molecular squares 3a,b and pi-complementary dioxoaryl cyclophanes. Single-crystal X-ray analyses of the [3]catenanes revealed the insertion of two aromatic units inside the metallocycle cavity. The structures are stabilized by means of a combination of pi-pi stacking, [C-H...pi] interactions, and [C-H...O] hydrogen bonds. [3]Catenane (DB24C8)2-(3a) showed in solid-state two external DB24C8 rings positioned over the Pd(en) corners, which are held in position by [N-H...O] hydrogen bonds. Furthermore, formation of catenane (DB24C8)2-(3a) can be switched off and on in a controllable manner by successive addition of KPF6 and 18-crown-6.

Synthesis of new self-assembled PdII and PtII rectangular metallomacrocycles: a comparative study of their inclusion complexes.

New palladium and platinum metallocycles have been synthesized by reacting 4,4'-bipyridinium-based ligands with PdII and PtII complexes. Strict thermodynamic self-assembly of 1 and [M(en)(NO3)2] (M=Pd, Pt) 6 a,b afforded metallocycles 7 a,b. However, the synthesis of 8 a,b and 9 a,b required a self-assembly process that used sodium p-phenylenediacetate (12) as a template. Finally, metallocycles 10 a,b were synthesized under high dilution conditions from ligand 4. The formation of inclusion complexes between metallocycles 7-10 and substrates 13 and 14 were studied by low-temperature 1H NMR, and the association constants were determined in nitromethane and water by following the characteristic charge-transfer band that these metallomacrocycles show in their UV-visible absorption spectra. A clear correlation between the affinity for a substrate and the dimensions of the metallocycle was observed. Metallocycles 8 b and 9 b exhibited the highest binding constants in water and nitromethane. This observation is in agreement with the DFT (B3LYP)-optimized geometries obtained for the different metallomacrocycles, which indicate that only macrocycles 8 and 9 possess a cavity with a width larger than 3.5 A. The insertion of hydroquinone or diol 13 into the cavity of metallocycle 11 a was confirmed by single-crystal X-ray crystallography.

Synthesis of [3]catenanes based on metal-directed self-assembly and pi-donor/pi-acceptor interactions.

A metal-directed self-assembly of [3]catenanes in combination with pi-pi interactions was investigated. Ligands based on 4,4'-bipyridinium or 2,7-diazapyrenium were used in conjunction with dioxoaryl cyclophanes (4-6) and trans-PdCl2(CH3CN)2. The [3]catenanes show a dinuclear palladium 46-membered metallomacrocycle interlocked by two pi-complementary dioxoaryl macrocycles. [structure: see text].

New hybrid [2]catenanes based on a 4,4'-bipyridinium ligand.

The self-assembly-mediated synthesis of metallomacrocycles 4a and 4b from (en)M(NO3)2 (M = Pd, Pt) and bipyridinium ligand 3 is described. The reaction is templated by disodium p-phenyldiacetic dicarboxylate, which is inserted into the macrocyclic cavity. Similarly, the self-assembly process between ligand 3, (en)M(NO3)2 (M = Pd, Pt), and the macrocyclic polyether 6 resulted in the formation of hybrid catenanes 7a and 7b. In the [2]catenanes, the circumrotation of the macrocyclic polyether through the cavity of the metallocycle is slow on the 1H NMR time scale.