Synthesis, characterisation and optical spectroscopy of platinum(ii) di-ynes and poly-ynes incorporating condensed aromatic spacers in the backbone

Abstract

A series of protected and terminal dialkynes with extended pi-conjugation through a condensed aromatic linker unit in the backbone, 1,4-bis(trimethylsilylethynyl)naphthalene, 1,4-bis(ethynyl)naphthalene, 9,10-bis(trimethylsilylethynyl)anthracene, 9,10-bis(ethynyl)anthracene, have been synthesized and characterized spectroscopically. The solid-state structures of and have been confirmed by single crystal X-ray diffraction studies. Reaction of two equivalents of the complex trans-[Ph(Et(3)P)(2)PtCl] with an equivalent of the terminal dialkynes 1,4-bis(ethynyl)benzene and, in (i)Pr(2)NH-CH(2)Cl(2), in the presence of CuI, at room temperature, afforded the platinum(II) di-ynes trans-[Ph(Et(3)P)(2)Pt-C[triple bond, length as m-dash]C-R-C[triple bond, length as m-dash]C-Pt(PEt(3))(2)Ph](R = benzene-1,4-diyl; naphthalene-1,4-diyl and anthracene-9,10-diyl ) while reactions between equimolar quantities of trans-[((n)Bu(3)P)(2)PtCl(2)] and under similar conditions readily afforded the platinum(II) poly-ynes trans-[-((n)Bu(3)P)(2)Pt-C[triple bond]C-R-C[triple bond]C-](n)(R = naphthalene-1,4-diyl and anthracene-9,10-diyl ). The Pt(II) diynes and poly-ynes have been characterized by analytical and spectroscopic methods, and the single crystal X-ray structures of and have been determined. These structures confirm the trans-square planar geometry at the platinum centres and the linear nature of the molecules. The di-ynes and poly-ynes are soluble in organic solvents and readily cast into thin films. Optical spectroscopic measurements reveal that the electron-rich naphthalene and anthracene spacers create strong donor-acceptor interactions between the Pt(II) centres and conjugated ligands along the rigid backbone of the organometallic polymers. Thermogravimetry shows that the di-ynes possess a somewhat higher thermal stability than the corresponding poly-ynes. Both the Pt(II) di-ynes and the poly-ynes exhibit increasing thermal stability along the series of spacers from phenylene through naphthalene to anthracene.

Ethynyltolan Platinum Complexes with (Arylalkynyl)phosphane Ligands

“…These values are unexceptional and similar to those found in other X-ray crystallographically characterised mononuclear P-coordinated alkynylphosphane- [8,10,14,15,26,27,61,62] or σ-alkynylplatinum [63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78] complexes. The C 6 H 4 group and the phenyl rings on each ethynyltolan ligand are nearly coplanar [dihedral angles: 2.89 (15) bon atoms of the proximal alkyne units (less than 3.4 Å, twice the van der Waals radius of the carbon atom).…”

Poly(anthrylenebutadiynylene)s: Precursor‐Based Synthesis and Band‐Gap Tuning

“…[9] However, the requisite 9,10-bis(ethynyl)anthracenes are unstable compounds, which poses a stumbling block for the preparation of well-characterized, high-molecular-weight materials. [10] To address this challenge, we explored a precursorpolymer-based approach using an established procedure for acene synthesis: the reductive aromatization of dihydroacenediols (Scheme 1). [11] This venerable method continues to be employed extensively for the preparation of acene hydrocarbons, including such challenging targets as hexacene and heptacene.…”

Recent Progress on the Photonic Properties of Conjugated Organometallic Polymers Built Upon the trans‐Bis(para‐ethynylbenzene)bis(phosphine)platinum(II) Chromophore and Related Derivatives

“…In fact, it is expected to be three orders of magnitude larger in 14 than in 4, so that the detection of the phosphorescence becomes very difficult in 14. [50] There is no evidence of observing any phosphorescence in thin films of 14. As there is greater delocalization within the anthryl group as compared to the phenylene spacer, the optical bandgap (the lowest energy HOMO-LUMO transition) as well as the triplet energy (T 1 !…”

“…Structures of the fully conjugated meso-substituted 1D zinc(porphyrin) oligomers (47 (n ¼ 6), 48 (n ¼ 3)) and the model compounds (49,50).…”