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Phosphole-substituted phosphaalkenes (PPAs) of the general formula Mes*PC(CH3)(C4H2P(Ph))R 5 a- c (Mes*=2,4,6- tBu3Ph; R=2-pyridyl ( a), 2-thienyl ( b), phenyl ( c)) have been prepared from octa-1,7-diyne-substituted phosphaalkenes by utilizing the Fagan-Nugent route. The presence of two differently hybridized phosphorus centers (σ2,λ3 and σ3,λ3) in 5 offers the possibility to selectively tune the HOMO-LUMO gap of the compounds by utilizing the different reactivity of the two phosphorus heteroatoms. Oxidation of 5 a- c by sulfur proceeds exclusively at the σ3,λ3-phosphorus atom, thus giving rise to the corresponding thioxophospholes 6 a- c. Similarly, 5 a is selectively coordinated by AuCl at the σ3,λ3-phosphorus atom. Subsequent second AuCl coordination at the σ2,λ3-phosphorus heteroatom results in a dimetallic species that is characterized by a gold-gold interaction that provokes a change in π conjugation. Spectroscopic, electrochemical, and theoretical investigations show that the phosphaalkene and the phosphole both have a sizable impact on the electronic properties of the compounds. The presence of the phosphaalkene unit induces a decrease of the HOMO-LUMO gap relative to reference phosphole-containing π systems that lack a PC substituent. [ABSTRACT FROM AUTHOR]

Homochiral and heterochiral cis-bis-cycloplatinated-[6]helicene derivatives 1 b1, 2, as representative examples of platina[6]helicenes that share a common platinum center, have been prepared. A diastereo- and enantioselective synthesis, which combines CH activation and dynamic isomerization from heterochiral structure 1 b2 into homochiral structure 1 b1, is also described. Overall, this isomerization process results in the transfer of chiral information from one helicene moiety to the other one. The chiroptical properties of homochiral ( P)- and ( M)- 1 b1 were greatly modified upon oxidation into their corresponding ( P)- and ( M)-diiodo-PtIV complexes ( 5). The changes were also analyzed by performing theoretical calculations. CH activation in the synthesis of organometallic helicenes is further demonstrated by the preparation of cis-bis-cycloplatinated-[8]helicene 1 c. [ABSTRACT FROM AUTHOR]

Three new 'short' metallacycles are selectively obtained from the reaction of a bimetallic CuI 'U-shape' molecular clip with, respectively, the cyano CN-, tricyanomethanide C(CN)3-, and azido N3- pseudohalogenide ions. These supramolecular assemblies have been characterized by spectroscopic methods, single-crystal X-ray diffraction, and elemental analysis. The single-crystal X-ray structures of these complexes reveal no short contact interaction between the pseudohalogenide ions within these self-assembled structures despite the short CuI…CuI distances within the molecular clips. The formation of these discrete metallacycles is rationalized by analyzing the structural features of the CuI 'U-shape' molecular clip. [ABSTRACT FROM AUTHOR]

A synthetic route to novel benzofuran-fused phosphole derivatives 3–5is described. These compounds showed optical and electrochemical properties that differ from their benzothiophene analog. Preliminary results show that 4can be used as an emitter in OLEDs, illustrating the potential of these new compounds for opto-electronic applications. [ABSTRACT FROM AUTHOR]

Introducing metal-vinyl ruthenium moieties onto [6]helicene results in a significant enhancement of the chiroptical properties due to strong metal-ligand electronic interactions. The electro-active Ru centers allow the achievement of the first purely helicene-based redox-triggered chiroptical switches. A combination of electrochemical, spectroscopic, and theoretical techniques reveals that the helicene moiety is a noninnocent ligand bearing a significant spin density. [ABSTRACT FROM AUTHOR]

A synthetic route to planar P-modified polycylic aromatic hydrocarbons (PAHs) is described. The presence of a reactive σ3,λ3-P moiety within the sp2-carbon scaffold allows the preparation of a new family of PAHs displaying tunable optical and redox properties. Their frontier molecular orbitals (MOs) are derived from the corresponding phosphole MOs and show extended conjugation with the entire p framework. The coordination ability of the P center allows the coordination-driven assembly of two molecular PAHs onto a AuΙ ion. [ABSTRACT FROM AUTHOR]

The photophysical electrochemical and optoelectronic properties of conjugated systems incorporating dibenzophosphole or phosphole moieties are described. Dibenzophosphole derivatives are not suitable materials for OLEDs due to their weak photoluminescence (PL) is the solid state and the instability of the devices. Variation of the substitution pattern of phospholes and chemical modification of their P atoms afford thermally stable derivatives, which are photo- and electroluminescent. Comparison of the optical properties of solution and thin film of thioxophospho as shows that these compounds do not form aggregates in the solid state. This property, which is also supported by an X-ray diffraction study of three novel derivatives results in an enhancement of the fluorescence quantum yields in the solid state. In contrast, (phosphole)gold(I) complexes exhibit a broad emission is this film, which is due to the formation of aggregates. Single and multilayer OLEDs using these P derivatives as the emissive layer have been fabricated. The emission color of these devices and their performances vary with the nature of the P material. Interestingly, di(2-thienyl)thiooxophosphole is an efficient host for the red dopant DCJTB, and devices using the gold complexes have broad emission spectra. [ABSTRACT FROM AUTHOR]

To study the ability of σ-P-P skeleton to mediate interaction between π-chromophores, 1,1'- biphospholes bearing phenyl or thienyl substituents at the 2,2' and 5,5'-position have been prepared and studied. These air-stable derivatives are readily available via a "one-pot" synthesis starting from diynes. Theoretical studies and UV-vis data clearly establish that the two π-systems interact via the σ-P-P bridge. This through-bond interaction results in a lowering of the optical HOMO-LUMO gap of the assembhes. The nucleophilic σ3-P centers of these 1 ,1'-biphospholes allow chemical modifications of the σ-bridge. These modifications offer further tuning of the optical properties of the assembly. Electrooxidation of the thienyl-substituted 1 ,1'-biphosphole results in electroactive materials characterized by low optical band gap and reversible p-doping. [ABSTRACT FROM AUTHOR]

Nickel(II)–diiminophosphorane complexes combined with alkylaluminum co-catalysts are active for the oligomerization of ethylene under biphasic reaction conditions. As observed in homogeneous phase, the selectivity (dimers vs higher oligomers) is related to the nature of the diiminophosphorane ligands. In 1-n-butyl-3-methylimidazolium organoaluminate ionic liquids, an enhancement of the catalytic activity and convergence of the selectivity are observed upon repeating cycles. These data suggest that organoaluminate anions replace the diiminophosphorane ligands in the coordination sphere of the active nickel species. [Copyright &y& Elsevier]

The coordination behaviour of the readily available 1-phenyl-2,5-di(2-pyridyl)phosphole (NPN) toward Ru centres was investigated. Neutral and ionic compounds of formula [RuCl(p-cymene)(NPN)]TfO (TfO=CF3SO3)… (1), [RuCl(p-cymene)(NPN)]BF4 (2), [RuCl(C6Me6)(NPN)]TfO (3), RuCp′Cl(NPN) [Cp′=C5H5 (4), C5Me5 (5)], Ru(C5Me5)(σ1-C8H13)(NPN) (6), RuCl2(NPN)2 (7) and RuClH(cod)(NPN) (cod=1,5-cyclooctadiene) (8) were obtained. Two diastereomers were obtained for 1, 2 and 4, (a, b) while three were found in the case of 8 (a–c). According to NMR spectroscopy, the 2,5-bis(2-pyridyl)phosphole acts as a 1,4-P,N chelate ligand in all cases. This behaviour was confirmed by an X-ray diffraction study performed on complex 1a. Proton transfer studies on complex 8 demonstrated the influence of the molecular structure on the ability to form dihydrogen bridges. [Copyright &y& Elsevier]

The first helicene-based carbene-osmium complex has been prepared from a vinyl-osmium derivative and this system has been shown to behave as a potential acid–base triggered chiroptical switch. [ABSTRACT FROM AUTHOR]

The article presents a study that shows the impact of metal center on chiroptical properties. It states that the nature of metal center has an effect on the chiroptical properties of the assemblies, opening a novel means of tuning the key property of chiral screw-shaped Π-conjugated structures. The theoretical analysis supported the process of stereoselective coordination of phosphole-modified azahelicenes top Pd11.

The reaction between a preassembled Cu I bimetallic molecular clip with a short intermetallic distance and a series of fully aliphatic cyano-capped ditopic linkers with increasing lengths was investigated. It is shown that, depending on the length of the ditopic linkers, the rational design of unprecedented supramolecular compact metallacycles containing fully aliphatic walls is possible. The specific preorganized molecular arrangement of the molecular clip used favors stabilizing interlinker London dispersion interactions, which allow, as the length of the linkers increases, the selective formation of discrete compact metallacycles at the expense of 1D coordination polymers. The generalizability of this approach was demonstrated by the reaction of fully aliphatic cyano-capped linkers with two other types of preassembled Cu I bimetallic molecular clips that also had short intermetallic distances., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Monometallic gold(I)-alkynyl-helicene complexes (1 a,b) and bimetallic gold(I)-alkynyl-helicene architectures featuring the presence (2 a,b) or absence (3 a,b) of aurophilic intramolecular interactions were prepared by using different types of phosphole ligands (mono-phosphole L1 or bis-phospholes L2,3). The influence of the Au(I) d(10) metal center(s) on the electronic, photophysical, and chiroptical properties of these unprecedented phosphole-gold(I)-alkynyl-helicene complexes was examined. Experimental and theoretical results highlight the importance of ligand-to-ligand-type charge transfers and the strong effect of the presence or absence of Au(I) -Au(I) interactions in 2 a,b., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The properties of mono- and bis-Ru-vinyl[6]helicene complexes (2 a and 2 b, respectively), recently synthesized by using molecular engineering of helicenes based on the grafting of lateral organometallic substituents on the π-helical backbone through a vinyl bridge, are presented. These helicene derivatives are thoroughly characterized, with special attention given to their chiroptical properties and redox switching activity. The UV/Vis and electronic circular dichroism (ECD) spectra of P and M enantiopure species, both in the neutral and oxidized states ([2 a](·+), [2 b](·+), and [2 b](2+)), are analyzed with the aid of quantum-chemical calculations. The extended π-conjugation facilitated by the vinyl moiety, clearly visible in the electronic structures of 2 a,b, introduces new active bands in the ECD spectra that consequently lead to a significant increase in optical rotation of Ru-vinylhelicenes compared with the organic precursors. The vibrational circular dichroism (VCD) spectra were measured and calculated for both the organic and organometallic species and constitute the first examples of VCD for metal-based helicene derivatives. Finally, the redox-triggered chiroptical switching activity of 2 a,b is examined in detail by using ECD spectroscopy. The modifications of the ECD spectra in the UV/Vis and NIR region are well reproduced and rationalized by calculations., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The straightforward synthesis of new supramolecular metallacycles having a 'pseudo double-paracyclophane' structure is presented. They are obtained from the reaction of a pre-assembled Cu(I) bimetallic precursor bearing short intermetallic distances with cyano-capped homoditopic π-conjugated linkers having flexible central cores.

We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P-containing PAHs exhibit properties expected for an emitter in white organic light-emitting diodes (WOLEDs)., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Reactions between the U-shaped binuclear Cu(I) complex A that bears short metal-metal distances and the cyano-capped monotopic π-conjugated ligands 1-5 that carry gradually bulkier polyaromatic terminal fragments lead to the formation of π-stacked supramolecular assemblies 6-10, respectively, in yields of 50-80 %. These derivatives have been characterized by multinuclear NMR spectroscopic analysis and X-ray diffraction studies. Their solid-state structures show the selective formation of U-shaped supramolecular assemblies in which two monotopic π-conjugated systems present large (6, 7, and 9) or medium (8 and 10) intramolecular π overlap, thus revealing π-π interactions. These assemblies self-organize into head-to-tail π-stacked dimers that in turn self-assemble to afford infinite columnar π stacks. The nature, extent, and complexity of the intermolecular contacts within the head-to-tail π-stacked dimer depend on the nature of the terminal polyaromatic fragment carried by the cyano-capped monotopic ligand, but it does not alter the result of the self-assembling process. These results demonstrate that the dinuclear molecular clip A that bears short metal-metal distances allows selective supramolecular assembly processes driven by the formation of intra- and intermolecular short π-π interactions in the resulting self-assembled structures; thus, demonstrating that their shape is not only dictated by the symmetry of the building blocks. This approach opens perspectives toward the formation of extended π-stacked columns based on dissymmetrical and functional π-conjugated systems., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The discovery and molecular engineering of novel electroluminescent materials is still a challenge in optoelectronics. In this work, the development of new π-conjugated oligomers incorporating a dihydrophosphete skeleton is reported. Variation of the substitution pattern of 1,2-dihydrophosphete derivatives and chemical modification of their P atoms afford thermally stable derivatives, which are suitable emitters to construct organic light-emitting diodes (OLEDs). The optical and electrochemical properties of these new P-based oligomers have been investigated in detail and are supported by DFT calculations. The OLED devices exhibit good performance and current-independent CIE coordinates., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Enantiopure mono-cycloplatinated-[8]helicene and bis-cycloplatinated-[6]helicene derivatives were prepared through column chromatography combined with crystallization of diastereomeric complexes using a chiral ancillary sulfoxide ligand. The UV-visible spectra, circular dichroism, molar rotations, and (circularly polarized) luminescence activity of these new helical complexes have been examined in detail and analysed with the help of first-principles quantum-chemical calculations.

Upon reaction with ligands A, 1 and 3 bearing the 2,5-bis(2-pyridyl)phosphole fragment, an unexpected conversion of Cu(II) metal centers to Cu(I) centers is observed affording either bimetallic complexes bearing a bridging phosphane coordination mode or hexametallic metallacycles.

The synthesis and chiroptical properties of chiral rhenium complexes bearing mono- or di-topic phosphole ligands are described.

Treatment of U-shaped, binuclear Cu(I) complexes 1,1' (1, counterion: BF(4)(-); 1', counterion: PF(6)(-)) with metal cyanide linear linkers K[Au(CN)(2)] (3) and Hg(CN)(2) (4) lead to formation of new supramolecular assemblies 5,5' and 6,6', respectively, in good yield. These derivatives have been characterized by NMR spectroscopy, IR, and X-ray diffraction studies. Derivative 5,5' are supramolecular metallacycles in which intramolecular aurophilic interactions between the Au(I) metal centers of the linkers are observed. Derivative 5 crystallizes as a single solid phase, whereas derivative 5' is characterized in the solid state as four different pseudo-polymorphs (5'a-d). Notably in the case of phase 5'd, a dimer of supramolecular metallacycles bounded by intermolecular aurophilic interactions is formed. Conversely, derivatives 6,6' present large structural diversity depending on the nature of the counterion. Derivative 6 is a supramolecular rectangle in which the Hg(II)-Hg(II) metal distance suggests mercurophilic interaction, whereas 6' crystallizes as two different pseudo-polymorphs 6'a,b, that is, a one-dimensional coordination polymer and one oligomer with no short Hg(II)-Hg(II) metal contacts, respectively. In derivatives 6,6', short contacts between the Hg(II) metal centers and fluorine atoms of the counterions are also observed, which may explain the counterion structural dependence of these supramolecular assemblies based on Hg(II) metal cyanide linker. Comparison of the different solid-state structures characterized highlights the importance of weak secondary interactions between the linkers for the formation supramolecular metallacycles from molecular clips 1,1' and suggests the range of energies required for these interactions to form metallacycles and to induce self-aggregation., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Acetylacetonato-platina[6]- and -platina[7]helicenes have been prepared from 2-pyridyl-substituted benzophenanthrene ligands by following a two-step cycloplatination reaction. The photophysical properties (UV-visible absorption and emission behavior) and chiroptical properties (circular dichroism and molar rotation) of the resolved enantiomers have been measured. These metallahelicenes constitute a novel family of easily accessible helicene derivatives that exhibit large and tuneable chiroptical properties that can be rationalized theoretically and compared to the parent [6]- and [7]carbohelicenes. Furthermore, they are red phosphors at room temperature and their large chiroptical properties can be modulated by oxidation of the metal center to Pt(IV). Hetero- and homochiral diastereomeric bis(metallahelicene)s that possess a rare Pt(III)-Pt(III) scaffold bridged by benzoato ligands have also been prepared. It is shown that the heterochiral (P,M)-bis(Pt(III)-[6]helicene) 9a(1) can isomerize into the homochiral (P,P)- and (M,M)-bis(Pt(III)-[6]helicene) 9a(2). Spectral assignments and an analysis of the optical rotation of these systems were made with the help of time-dependent density functional theory. The calculations highlight the contributions of the metal centers to the chiroptical properties. For 9a(1) and 9a(2), σ-π conjugation between the helicenes and the Pt-Pt moiety may contribute strongly to the optical rotation and electronic circular dichroism., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The reaction of the [{CpMo(CO)(2)}(2)(μ,η(2):η(2)-P(2))] (Cp=cyclopentadienyl) metallo-ligand 2 with pre-organized Cu(I) bi- and trimetallic precursors afforded new coordination complexes with unprecedented coordination modes for a Mo(2)P(2) complex. Variable-temperature solution and solid-state (31)P NMR spectroscopy measurements were performed and X-ray diffraction studies revealed an η(2):η(1) coordination mode for the Mo(2)P(2) unit of 2 in the Cu(I) bimetallic complexes 3 and 4. DFT calculations were carried out to highlight the bonding situation of this unprecedented coordination mode in the Cu(I) bimetallic compound 3. It is built up from a side-on coordination of the P-P σ bond to one copper ion and from the interaction of the lone pair of one phosphorus atom with the second copper ion. The remaining available lone pair of the second phosphorus atom can be involved as well to interact with an additional metal centre, as evidenced in the Cu(I) trimetallic compound 5 in which an η(2):η(1):η(1) coordination mode of the ligand 2 is observed. Derivative 3 can be used as a molecular clip to obtain discrete π-stacked dimers through a ligand exchange reaction between acetonitrile ligands and cyano-capped π-conjugated systems, indicating the stability of the new η(2):η(1) coordination mode., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Supramolecular extended frameworks based on a rotational molecular clip and having the same "primary structure" can exhibit either an unfolded or a folded framework. This process is driven by intramolecular π-π interactions, resulting in the formation of an infinite π-stacked column within the folded supramolecular framework.

Hetero- and homochiral diastereomeric bis(metallahelicene)s have been synthesized. They possess a rare Pt(III)-Pt(III) scaffold bridged by benzoato ligands. It is shown that heterochiral (P,M)-bis(Pt(III)-[6]helicene) can isomerize into the homochiral (P,P)- and (M,M)-bis(Pt(III)-[6]helicene). A theoretical study shows a unique σ-π conjugation between the two π-helices and the σ-Pt(III)-Pt(III) scaffold that impacts the strong chiroptical properties.

Chiral, π-conjugated 3,4-butano-1-phenyl-2,5-bis(2-pyridyl)phosphole derivatives 1a(2,2') and 1a(3) with chiral trans-1,2-diol moieties and fused pinene derivatives, respectively, were prepared from the corresponding chiral diynes by using the Fagan-Nugent method. Their UV/Vis absorption and chiroptical properties (optical rotation and circular dichroism) were studied. Their behavior as N,P,N chelates towards coordination of Cu(I) and formation of chiral supramolecular assemblies with π-conjugated ditopic dicyano ligands was investigated. Chiral C(2)-symmetric rectangles that are [2,2]paracyclophane analogues were obtained, as demonstrated by X-ray crystallography. During the course of this study, the first stable water-soluble phosphole derivative (1a(2)·2 HCl) was prepared. Furthermore, achiral 3,4-butano-1-phenyl-2,5-bis(aza[4]helicene)phosphole 1a(4) was synthesized and displays extended π conjugation. A supramolecular rectangle was obtained by coordination to Cu(I) and assembly with a dicyano stilbene. This coordination-driven supramolecular assembly contains a total of four aza[4]helicene moieties and displays two types of π-π stacking interactions in the solid state, that is, between two helicene moieties and between one helicene and a bridging dicyano ligand. All the supramolecular arrangements are discussed by comparing them with previous work on the parent 3,4-butano-1-phenyl-2,5-bis(2-pyridyl)phosphole., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Conjugated systems based on phospholes and 1,1'-biphospholes bearing 3,4-ethylenedithia bridges have been prepared using the Fagan-Nugent route. The mechanism of this organometallic route leading to intermediate zirconacyclopentadienes has been investigated by using theoretical calculations. This study revealed that the oxidative coupling leading to zirconacyclopentadienes is favored over oxidative addition within the S-C≡C bond both thermodynamically and kinetically. The impact of the presence of the S atoms on the optical and electrochemical behavior of the phospholes and 1,1'-biphospholes has been systematically evaluated both experimentally and theoretically. A comparison with their "all-carbon" analogues is provided. Of particular interest, this comparative study revealed that the introduction of S atoms has an impact on the electronic properties of phosphole-based conjugated systems. A decrease of the HOMO-LUMO separation and a stabilization of the LUMO level were observed. These general trends are also observed with 1,1'-biphospholes exhibiting σ-π conjugation. The P atom of the 3,4-ethylenedithiaphospholes can be selectively oxidized by S(8) or O(2). These P modifications result in a lowering of the HOMO-LUMO separation as well as an increase of the reduction and oxidation potentials. The S atoms of the 3,4-ethylenedithia bridge of the 2,5-phosphole have been oxidized using m-chloroperoxybenzoic acid. The resulting 3,4-ethylenesulfoxide oxophosphole was characterized by an X-ray diffraction study. Experimental and theoretical studies show that this novel chemical manipulation results in an increase of the HOMO-LUMO separation and an important decrease of the LUMO level. The electropolymerization of 2-thienyl-capped 3,4-ethylenedithiathioxophosphole and 1,1'-biphosphole is reported. The impact of the S substituents on the polymer properties is discussed.

The reaction of U-shaped, bimetallic, Cu(I) complexes, assembled from a heteroditopic pincer, with cyano-capped pi-conjugated linkers gives a straightforward access to pi-stacked metallocyclophanes in good yields. In these assemblies, the pi-walls have an almost face-to-face arrangement. The versatility of this rational supramolecular synthesis is demonstrated with the use of linkers that have nanoscale lengths (up to 27.7 A), different chemical compositions (oligo(para-phenylenevinylene)s OPVs, oligo(phenylene)s, oligo(phenylethynylene)s), and alternative geometries (linear, angular). Linkers that incorporate an internal pyridyne moiety can also be employed. X-ray diffraction studies revealed that the metallocyclophanes based on linear linkers self-organize into infinite pi-stacked columns in the solid state with intermolecular distances of about 3.6 A. This approach, based on coordination-driven self-assembly, provides a novel and rational strategy for the stacking of extended pi-systems in the solid state.

Aza[n]helicene phosphole derivatives have been prepared from aza[n]helicene diynes by the Fagan-Nugent route. Their photophysical properties (UV/Vis absorption and emission behavior) have been evaluated. Their behavior as P,N chelates towards coordination to Pd(II) and Cu(I) has been investigated: metal-bis(aza[n]helicene phosphole) assemblies are formed by a highly stereoselective coordination process, as demonstrated by X-ray crystallography. An aza[6]helicene phosphole bearing an enantiopure helicene part has been obtained, which allows the preparation of enantiopure Pd(II) and Cu(I) complexes with original topologies and high molar rotation (MR) and circular dichroism (CD). The structure-property relationship established from the experimental data has been studied in detail by theoretical studies (TDDFT calculations of UV/Vis, CD, and MR). Aza[n]helicene phosphole derivatives show pi conjugation extended over the entire molecule, and its influence on the MR of aza[6]helicene phosphole 5 c has been demonstrated. Finally, it has been shown that the nature of the metal (coordination geometry and electronic interaction) can have a great impact on the amplitude of the chiroptical properties in metal-bis(aza[n]helicene phosphole) assemblies.

Bridging ligands in Ag(I) and Au(I) bimetallic complexes: The P moiety of bis(2-pyridyl)phosphole acts as a symmetrically, semi-, or non-bridging donor in Ag(I) dimers (see figure). In related Au(I) complexes, only the non-bridging mode is observed. An unsaturated Ag(I) dimer is used as an adaptive molecular clip for the synthesis of pi-stacked metallocyclophanes.Bis(2-pyridyl)phosphole C reacted with AgPF(6) and dppm giving rise to dicationic dimer 1 in which C acts as a 1kappaN:1,2kappaP:2kappaN-donor with a symmetrically bridging P-centre. This complex gives the first example of dimers based on trigonal planar metal centres bearing a bridging sigma(3),lambda(3)-phosphane ligand. The reaction of two equivalents of C with AgPF(6) and Ag{Al[OC(CF(3))(3)](4)} afforded dicationic dimers 2 and 3 of general formula Ag(2)(C)(2) (2+), respectively. X-ray diffraction studies showed that one ligand C acts as a 1kappaN:1,2kappaP:2kappaN-donor with a symmetrically bridging P-centre and one behaves as a 1kappaN:2kappaP-chelate. In complex 3, one toluene molecule interacts with an Ag centre, giving the first example of a mixed coordination dimer featuring a bridging P-donor. Ag(I)-dimers 4 a-c of the general formula Ag(2)(C)(3) (2+), 2 X(-) (X=PF(6), BF(4), Al[OC(CF(3))(3)](4)) have been prepared according to different routes and characterised by X-ray diffraction study. In these derivatives, C exhibits a variety of coordination modes depending on the nature of the counteranion and of the solvent molecules included in the asymmetric units. These complexes can feature 0, 1, or 2 bridging P-donors. These results definitively demonstrate that the P-centre of phosphane ligands can easily switch from a bridging to a semi-bridging and a non-bridging coordination mode. Dimer 2 is used as an "adaptive" molecular clip for the synthesis of pi-stacked metallocyclophanes 7 a, b and 8 upon reaction with ditopic linkers. X-ray diffraction studies revealed that these supramolecular species behave as receptors for the counteranions (PF(6), BF(4)) and that the nature of the anion impacts the stereochemistry of the supramolecular metallocyclophanes. Au(I)-Dimers 10 a, b bearing two ligands C acting as 1kappaN:2kappaP-chelates are prepared and characterised in the solid-state.

Two series of phospholes and 1,1'-biphospholes bearing either 2- or 3-thienyl substituents at the C atoms are prepared by using the Fagan-Nugent route. Their optical (UV/Vis absorption, fluorescence spectra) and electrochemical properties are systematically evaluated. Of particular interest, the first ever reported 3-thienyl-substituted phospholes exhibit higher LUMO levels than their 2-thienyl analogues, and show accordingly different physical properties. This study also reveals that the 1,1'-biphospholes exhibit sigma-pi conjugation. The phosphole and 1,1'-biphosphole derivatives bearing 3-thienyl substituents are characterized by X-ray diffraction study. The structure-property relationship established following the experimental data are fully supported by theoretical studies including time-dependent(TD)-DFT spectra. A photocyclization reaction performed on the thioxo- and oxophospholes having 3-thienyl substituents affords a novel ring-fused phosphole-thiophene derivative, which was characterized by an X-ray diffraction study. The structure and electronic properties of this novel dithienophosphole are discussed based on experimental and theoretical data.

pi-Conjugated organophosphorus derivatives have recently emerged as valuable building blocks for the tailoring of functional molecular materials. We have focused for ten years on the synthesis of phospholes bearing aromatic 2,5-substituents (phenyl, thienyl, pyridyl, etc.) and used these compounds as materials in fields as diverse as OLED's, WOLED's, non linear optics. Their properties (such as optical and electrochemical behaviour, thermal stability) can be finely tuned by functionalization at the P atom. Phosphole-based polymers have also been prepared by electropolymerization and have been used as sensors. More recently, phospholes substituted by one or two pyridyl groups have proven to act as multidentate ligands with original coordination properties. A diversity of supramolecular rectangles that stacked into columns in the solid state has been obtained, opening new perspectives in the coordination-driven supramolecular organization of pi-conjugated systems. Chiral pi-conjugated phospholes having a helical moiety have also been synthesized and spatially organized by using coordination to metallic ions, giving rise to sophisticated chiral complexes.

EDOT-capped sigma3-phosphole self-rigidifies due to an unprecedented P-O interaction and can be electropolymerised affording functionalizable polymers.

Phosphole-modified aza[4]helicenes act as heteroditopic chelates toward metal ions having different coordination geometries (Pd(II), Cu(I)).

Bis(2-pyridyl)phosphole 1 reacted with Cu(I) sources giving rise to dicationic or neutral dimers 2,3. In these derivatives, 1 acts as a 1kappaN:1,2kappaP:2kappaN donor with a symmetrically bridging P centre. X-ray diffraction studies of these species revealed no constraint due to the unusual coordination mode of the P donor. A comparative study with a monometallic Cu(I) complex in which 1 acts as a P,N chelate is presented. The acetonitrile ligands of the dicationic complex 2 can be displaced by a variety of donors. Bipyridine (bipy) acts as a chelating donor, while 1,1'-bis(diphenylphosphino)methane (dppm) and bis(2-pyridyl)phosphole 1 behave as bridging ligands. By using dppm and 1, the complexes arising from the stepwise displacement of the acetonitrile ligands of complex 2 can be isolated. X-ray diffraction studies performed on these novel complexes revealed that the P centre can easily switch from a bridging to a semibridging coordination mode. Of particular interest, within the same unit cell, complexes with P centres exhibiting bridging and semibridging coordination modes are observed. This switching can be induced by weak effects such as a different conformation of the incoming ligand. Cu(I) dimers assembled by 1 are air-stable derivatives that are not water sensitive. Hydrolysis of the PF(6) (-) counterion occurs under drastic conditions and results in the formation of a PO(2)F(2) fragment coordinated to a Cu(I)-1 fragment.

Herein, a Raman spectroscopic study of a new family of 2,5-di(2-thienyl)phospholes and thienyl-capped 1,1'-diphospholes is presented. The Raman spectra have been carefully assigned with the help of density functional calculations. For di(2-thienyl)phospholes, two well-differentiated groups of Raman bands exist that arise either from the central phosphole ring or from the outer thiophene substituents. These data reveal a segmentation of the electronic structure. This paper reports interesting relationships between geometrical data such as the BLA (bond-length alternation) parameter and Raman band wavenumbers. These correlations are unprecedented in the chemistry of phospholes and have been used to interpret the evolution of the electronic structure (aromaticity=pi-conjugation) upon 1) substitution of the central sulfur atom of terthiophene by phosphorus and 2) P-functionalization. Increasing the coordination number of the phosphole ring results in intramolecular charge transfer. The best scenario for phosphole aromaticity is found for 1,1'-diphospholes.

Self-assembly of CuI dimers, featuring a bridging phosphole ligand, and ditopic cyano-substituted chromophores affords nanosize supramolecular cationic rectangles. Due to the short Cu-Cu distance in the bimetallic clips, the coordinated chromophores are forced to participate in cofacial pi-pi interactions as evidenced by X-ray data. In addition, intermolecular pi-pi interactions in the solid state are observed leading to infinite columns of pi-stacked (para-phenylenevinylene)-based chromophores.

The photophysical, electrochemical, and optoelectronic properties of conjugated systems incorporating dibenzophosphole or phosphole moieties are described. Dibenzophosphole derivatives are not suitable materials for OLEDs due to their weak photoluminescence (PL) in the solid state and the instability of the devices. Variation of the substitution pattern of phospholes and chemical modification of their P atoms afford thermally stable derivatives, which are photo- and electroluminescent. Comparison of the optical properties of solution and thin film of thioxophospholes shows that these compounds do not form aggregates in the solid state. This property, which is also supported by an X-ray diffraction study of three novel derivatives, results in an enhancement of the fluorescence quantum yields in the solid state. In contrast, (phosphole)gold(I) complexes exhibit a broad emission in thin film, which is due to the formation of aggregates. Single- and multilayer OLEDs using these P derivatives as the emissive layer have been fabricated. The emission color of these devices and their performances vary with the nature of the P material. Interestingly, di(2-thienyl)thiooxophosphole is an efficient host for the red dopant DCJTB, and devices using the gold complexes have broad emission spectra.

The homodimeric flavoprotein glutathione reductase (GR) is a central player of cellular redox metabolism, connecting NADPH to the large pool of redox-active thiols. In this work, the inhibition of human GR by a novel gold-phosphole inhibitor (GoPI) has been studied in vitro. Two modes of inhibition are observed, reversible inhibition that is competitive with GSSG followed by irreversible inhibition. When approximately 1 nm GoPI is incubated with NADPH-reduced GR (1.4 nm) the enzyme becomes 50% inhibited. This appears to be the most potent stable inhibitor of human GR to date. Analyzing the monophasic oxidative half-reaction of reduced GR with GSSG at pH 6.9 revealed a K(d)((app)) for GSSG of 63 microm, and a k((obs)max) of 106 s(-1) at 4 degrees C. The reversible inhibition by the gold-phosphole complex [{1-phenyl-2,5-di(2-pyridyl)phosphole}AuCl] involves formation of a complex at the GSSG-binding site of GR (K(d) = 0.46 microm) followed by nucleophilic attack of an active site cysteine residue that leads to covalent modification and complete inactivation of the enzyme. Data from titration spectra, molecular modeling, stopped-flow, and steady-state kinetics support this theory. In addition, covalent binding of the inhibitor to human GR was demonstrated by mass spectrometry. The extraordinary properties of the compound and its derivatives might be exploited for cell biological studies or medical applications, e.g. as an anti-tumor or antiparasitic drug. Preliminary experiments with glioblastoma cells cultured in vitro indicate an anti-proliferative effect of the inhibitor in the lower micromolar range.

[structure: see text] Alternating thiophene-phosphole oligomers up to seven rings in length have been synthesized. A regular decrease of the HOMO-LUMO gap is observed upon increasing the length of the pi-conjugated system. The nature of the P-moieties dramatically influences the optical and electrochemical properties of these phosphole-based oligomers. Electro-oxidation of derivative 5a afforded an electroactive polymer exhibiting reversible p-doping.

Two synthetic routes to Pd(I) dimers that feature a bridging 1-phenyl- and 1-cyclohexyl-2,5-di(2-pyridyl)phosphole ligand, 3 a and 3 b, respectively, are described. The first involves a conproportionation process between Pd(II) and Pd(0) complexes, while the second involves ligand displacement from a preformed Pd(I) dimer. Both routes are operable for 1-phenylphosphole 1 a, whereas the former failed with 1-cyclohexylphosphole 1 b. A mechanistic study revealed that the conproportionation pathway implies a reversible oxidative addition of the P-C(phenyl) bond of Pd(II)-coordinated 1 a to Pd(0) leading to a bimetallic Pd(II) complex 5. The structures of complexes 3 a and 3 b were studied by means of X-ray diffraction. The similarity of these solid-state structures suggests that the bridging mode of the P atom is due to mu-1kappaN:1,2kappaP:2kappaN coordination of ligands 1 a, b. The electrochemical behaviour and UV/Vis absorption properties of complexes 3 a, b are reported. Complex 3 a is inert towards CO, PPh(3) and 1,3-dipoles. It reacted with dimethylacetylene dicarboxylate to give complex 6 as a result of insertion of the alkyne into the Pd-Pd bond. X-ray diffraction studies of complexes 5 and 6 are also presented.