Electronic and steric effects of platinum(ii) di-yne and poly-yne substituents on the photo-switching behaviour of stilbene: experimental and theoretical insights.

A series of mono-, di-, and poly(platina-ynes) incorporating stilbene spacer units with the formulae trans-[R-C[triple bond, length as m-dash]C-Pt(PBu3)2-C[triple bond, length as m-dash]C-R] (R = (E)-1,2-diphenylethene), trans-[(Ph)-(Et3P)2PtC[triple bond, length as m-dash]C-R-C[triple bond, length as m-dash]CPt(PEt3)2(Ph)] (R = (E)-1,2-diphenylethene), and trans-[-(PnBu3)2PtC[triple bond, length as m-dash]C-R-C[triple bond, length as m-dash]C-]n (R = (E)-1,2-diphenylethene), respectively, have been synthesized and characterized to explore the effects of ligand topology on the photoisomerization and photophysical properties of these materials. The structural and photophysical properties of the complexes have been investigated and compared with those of the previously reported mono-, di- and poly(platina-ynes) incorporating azobenzene spacers. We found that the organometallic species 1M, 2M and 1P undergo topology-dependent reversible trans-to-cis photoisomerization in CH2Cl2 solution. Computational modelling supported the experimental findings.

Utilization of a Pt(ii) di-yne chromophore incorporating a 2,2'-bipyridine-5,5'-diyl spacer as a chelate to synthesize a green and red emitting d-f-d heterotrinuclear complex.

A new heterotrinuclear (d-f-d) complex [Eu(btfa)31c] (btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedione and 1c = [(Ph)(Et3P)2Pt-C[triple bond, length as m-dash]C-R-C[triple bond, length as m-dash]C-Pt(Et3P)2(Ph)] (R = 2,2'-bipyridine-5,5'-diyl) has been synthesized by utilizing the N,N-donor sites of the organometallic chromophore. The complex was characterized by analytical and spectroscopic methods. Photophysical properties of the complex were analysed in detail using both steady-state and time-resolved emission and excitation spectroscopy. The optical absorption spectrum of the complex is dominated by the spin allowed π-π* transitions of the btfa and 1c units in the UV-visible region (200-418 nm) and thus is excitable over a wide range of wavelengths across the UV into the visible region of the electromagnetic spectrum. The complex displays typical red Eu(iii) emission when excited at 345 nm. However, it also shows green emission when excited at 464 nm and, thus could be an interesting candidate for full colour display applications. The change in the colour could be a result of the high value of the energy back-transfer rate (6.73 × 105 s-1) from the triplet state of the organometallic chromophore to the 5D1 state of Eu(iii). Judd-Ofelt (J-O) intensity parameters (Ω2 and Ω4), radiative (AR), non-radiative (AR) decay rates and intrinsic quantum yield (Q) have been calculated.

Correction: Utilization of a Pt(II) di-yne chromophore incorporating a 2,2'-bipyridine-5,5'-diyl spacer as a chelate to synthesize a green and red emitting d-f-d heterotrinuclear complex.

Correction for 'Utilization of a Pt(ii) di-yne chromophore incorporating a 2,2'-bipyridine-5,5'-diyl spacer as a chelate to synthesize a green and red emitting d-f-d heterotrinuclear complex' by Idris Juma Al-Busaidi et al., Dalton Trans., 2021, DOI: 10.1039/d0dt04198j.

Two Is Better than One? Investigating the Effect of Incorporating Re(CO)3Cl Side Chains into Pt(II) Diynes and Polyynes.

Pt(II) diynes and polyynes incorporating 5,5'- and 6,6'-disubstituted 2,2'-bipyridines were prepared following conventional Sonogashira and Hagihara dehydrohalogenation reaction protocols. Using Pt(II) dimers and polymers as a rigid-rod backbone, four new heterobimetallic compounds incorporating Re(CO)3Cl as a pendant functionality in the 2,2'-bipyridine core were obtained. The new heterobimetallic Pt-Re compounds were characterized by analytical and spectroscopic techniques. The solid-state structures of a Re(I)-coordinated diterminal alkynyl ligand and a representative model compound were determined by single-crystal X-ray diffraction. Detailed photophysical characterization of the heterobimetallic Pt(II) diynes and polyynes was carried out. We find that the incorporation of the Re(CO)3Cl pendant functionality in the 2,2'-bipyridine-containing main-chain Pt(II) diynes and polyynes has a synergistic effect on the optical properties, red shifting the absorption profile and introducing strong long-wavelength absorptions. The Re(I) moiety also introduces strong emission into the monomeric Pt(II) diyne compounds, whereas this is suppressed in the polyynes. The extent of the synergy depends on the topology of the ligands. Computational modeling was performed to compare the energetic stabilities of the positional isomers and to understand the microscopic nature of the major optical transitions. We find that 5,5'-disubstituted 2,2'-bipyridine systems are better candidates in terms of yield, photophysical properties, and stability than their 6,6'-substituted counterparts. Overall, this work provides an additional synthetic route to control the photophysical properties of metallaynes for a variety of optoelectronic applications.

Rise of Conjugated Poly-ynes and Poly(Metalla-ynes): From Design Through Synthesis to Structure-Property Relationships and Applications.

Conjugated poly-ynes and poly(metalla-ynes) constitute an important class of new materials with potential application in various domains of science. The key factors responsible for the diverse usage of these materials is their intriguing and tunable chemical and photophysical properties. This review highlights fascinating advances made in the field of conjugated organic poly-ynes and poly(metalla-ynes) incorporating group 4-11 metals. This includes several important aspects of conjugated poly-ynes viz. synthetic protocols, bonding, electronic structure, nature of luminescence, structure-property relationships, diverse applications, and concluding remarks. Furthermore, we delineated the future directions and challenges in this particular area of research.