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Multi-branched molecules have recently demonstrated interesting behaviour as charge-transporting materials within the fields of perovskite solar cells (PSCs). For this reason, extended triarylamine dendrons have been grafted onto a pillar[5]arene core to generate dendrimer-like compounds, which have been used as hole-transporting materials (HTMs) for PSCs. The performances of the solar cells containing these novel compounds have been extensively investigated. Interestingly, a positive dendritic effect has been evidenced as the hole transporting properties are improved when going from the first to the second-generation compound. The stability of the devices based on the best performing pillar[5]arene material has been also evaluated in a high-throughput ageing setup for 500 h at high temperature. When compared to reference devices prepared from spiro-OMeTAD, the behaviour is similar. An analysis of the economic advantages arising from the use of the pillar[5]arene-based material revealed however that our pillar[5]arene-based material is cheaper than the reference., (© 2021 Wiley-VCH GmbH.)

Invited for the cover of this issue are the groups of S. Seki (Kyoto), G. Reginato (Sesto Fiorentino), J.-F. Nierengarten (Strasbourg), A. Abate (Berlin) and J. L. Delgado (San Sebastian). The image depicts an artistic view of a dendrimer-like hole transporting material at work in a perovskite solar cell. Read the full text of the article at 10.1002/chem.202101110., (© 2021 Wiley-VCH GmbH.)

The reaction of [CpRuCl(PPh(3))(2)] (Cp = cyclopentadienyl) and [CpRuCl(dppe)] (dppe = Ph(2)PCH(2)CH(2)PPh(2)) with bis- and tris-phosphine ligands 1,4-(Ph(2)PC[triple bond]C)(2)C(6)H(4) (1) and 1,3,5-(Ph(2)PC[triple bond]C)(3)C(6)H(3) (2), prepared by Ni-catalysed cross-coupling reactions between terminal alkynes and diphenylchlorophosphine, has been investigated. Using metal-directed self-assembly methodologies, two linear bimetallic complexes, [{CpRuCl(PPh(3))}(2)(mu-dppab)] (3) and [{CpRu(dppe)}(2)(mu-dppab)](PF(6))(2) (4), and the mononuclear complex [CpRuCl(PPh(3))(eta(1)-dppab)] (6), which contains a "dangling arm" ligand, were prepared (dppab =1,4-bis[(diphenylphosphino)ethynyl]benzene). Moreover, by using the triphosphine 1,3,5-tris[(diphenylphosphino)ethynyl]benzene (tppab), the trimetallic [{CpRuCl(PPh(3))}(3)(mu(3)-tppab)] (5) species was synthesised, which is the first example of a chiral-at-ruthenium complex containing three different stereogenic centres. Besides these open-chain complexes, the neutral cyclic species [{CpRuCl(mu-dppab)}(2)] (7) was also obtained under different experimental conditions. The coordination chemistry of such systems towards supramolecular assemblies was tested by reaction of the bimetallic precursor 3 with additional equivalents of ligand 2. Two rigid macrocycles based on cis coordination of dppab to [CpRu(PPh(3))] were obtained, that is, the dinuclear complex [{CpRu(PPh(3))(mu-dppab)}(2)](PF(6))(2) (8) and the tetranuclear square [{CpRu(PPh(3))(mu-dppab)}(4)](PF(6))(4) (9). The solid-state structures of 7 and 8 have been determined by X-ray diffraction analysis and show a different arrangement of the two parallel dppab ligands. All compounds were characterised by various methods including ESIMS, electrochemistry and by X-band ESR spectroscopy in the case of the electrogenerated paramagnetic species.