Synthesis, Mesomorphism, and Photophysics of 2,5-Bis(dodecyloxyphenyl)pyridine Complexes of Platinum(IV)

TY - JOUR

T1 - Synthesis, Mesomorphism, and Photophysics of 2,5-Bis(dodecyloxyphenyl)pyridine Complexes of Platinum(IV)

AU - Parker, Rachel Roberta

AU - Sarju, Julia Paula

AU - Whitwood, A.C.

AU - Williams, J. A. Gareth

AU - Lynam, Jason Martin

AU - Bruce, Duncan Watson

N1 - © 2018 Wiley-VCH. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.

PY - 2018/12/17

Y1 - 2018/12/17

N2 - Abstract: It has been shown for the first time that the PtIVcomplex cis-[Pt(N^C-tolpy)2Cl2] (tolpy=2-(4-tolyl)pyridinyl)can be prepared in a one-pot reaction from K2[PtCl4], althoughanalogous complexes containing 2,5-bis(4-dodecyloxyphenyl)pyridine (=HL) could be prepared using existingroutes. The resulting complexes cis-[Pt(N^C-L)2Cl2] are liquidcrystals and small-angle X-ray scattering suggests formationof a lamellar mesophase. Surprisingly, heating [Pt(k2-N^CL)2Cl(k1-N^C-LH)] also leads to a mesomorphic compound,which results from thermally induced oxidation to cis-[Pt(N^C-L)2Cl2] and what is presumed to be another geometricisomer of the same formula. The PtIV complexes are quitestrongly luminescent in deoxygenated solution, with f10% and show vibrationally structured emission spectra,lmax(0,0)=532 nm, strongly displaced to the red comparedto cis-[Pt(N^C-tolpy)Cl2]. Long luminescence lifetimes of230 ms are attributed to a lower degree of metal character inthe excited state accompanying the extension of conjugationin the ligand. There is no significant difference betweenthe emission properties of the bromo- and chloro-complexes,in contrast with the known complexes cis-[Pt(N^Cppy)X2], where the quantum yield for X=Br is some30 times lower than for X=Cl (ppyH=2-phenylpyridine).The lower energy of the excited state in the new complexesprobably ensures that deactivating LLCT/LMCT states remainthermally inaccessible, even when X=Br.

AB - Abstract: It has been shown for the first time that the PtIVcomplex cis-[Pt(N^C-tolpy)2Cl2] (tolpy=2-(4-tolyl)pyridinyl)can be prepared in a one-pot reaction from K2[PtCl4], althoughanalogous complexes containing 2,5-bis(4-dodecyloxyphenyl)pyridine (=HL) could be prepared using existingroutes. The resulting complexes cis-[Pt(N^C-L)2Cl2] are liquidcrystals and small-angle X-ray scattering suggests formationof a lamellar mesophase. Surprisingly, heating [Pt(k2-N^CL)2Cl(k1-N^C-LH)] also leads to a mesomorphic compound,which results from thermally induced oxidation to cis-[Pt(N^C-L)2Cl2] and what is presumed to be another geometricisomer of the same formula. The PtIV complexes are quitestrongly luminescent in deoxygenated solution, with f10% and show vibrationally structured emission spectra,lmax(0,0)=532 nm, strongly displaced to the red comparedto cis-[Pt(N^C-tolpy)Cl2]. Long luminescence lifetimes of230 ms are attributed to a lower degree of metal character inthe excited state accompanying the extension of conjugationin the ligand. There is no significant difference betweenthe emission properties of the bromo- and chloro-complexes,in contrast with the known complexes cis-[Pt(N^Cppy)X2], where the quantum yield for X=Br is some30 times lower than for X=Cl (ppyH=2-phenylpyridine).The lower energy of the excited state in the new complexesprobably ensures that deactivating LLCT/LMCT states remainthermally inaccessible, even when X=Br.

UR - http://www.scopus.com/inward/record.url?scp=85056622312&partnerID=8YFLogxK

U2 - 10.1002/chem.201804026

DO - 10.1002/chem.201804026

M3 - Article

SN - 0947-6539

VL - 24

SP - 19010

EP - 19023

JO - Chemistry : A European Journal

JF - Chemistry : A European Journal

IS - 71

ER -