The development of synthetic strategies to engineer π-conjugated polymers is of paramount importance in modern chemistry and materials science. Here we introduce a synthetic protocol based on the search for specific vibrational modes through an appropriate tailoring of the π-conjugation of the precursors, in order to increase the attempt frequency of a chemical reaction. First, we design a 1D π-conjugated polymer on Au(111), which is based on bisanthene monomers linked by cumulene bridges that tune specific vibrational modes. In a second step, upon further annealing, such vibrational modes steer the twofold cyclization reaction between adjacent bisanthene moieties, which gives rise to a long pentalene-bridged conjugated ladder polymer featuring a low bandgap. In addition, high resolution atomic force microscopy allows us to identify by atomistic insights the resonance form of the polymer, thus confirming the validity of the Glidewell and Lloyd´s rules for aromaticity. This on-surface synthetic strategy may stimulate exploiting previously precluded reactions towards π-conjugated polymers with specific structures and properties.

Departamento de Física de la Materia Condensada Universidad Autónoma de Madrid Cantoblanco Madrid Spain

Departamento de Química Orgánica Facultad de Ciencias Químicas Universidad Complutense 28040 Madrid Spain

IMDEA Nanociencia C Faraday 9 Ciudad Universitaria de Cantoblanco 28049 Madrid Spain

Institute of Physics The Czech Academy of Sciences Cukrovarnická 10 162 00 Prague 6 Czech Republic

Regional Centre of Advanced Technologies and Materials Palacký University Šlechtitelů 27 783 71 Olomouc Czech Republic

See more in PubMed

Heeger AJ. Semiconducting and metallic polymers: the fourth generation of polymeric materials (Nobel Lecture) Angew. Chem. Int. Ed. 2001;40:2591–2611. PubMed

Guo X, Baumgarten M, Müllen K. Designing π-conjugated polymers for organic electronics. Prog. Polym. Sci. 2013;38:1832–1908.

Facchetti A. Π-conjugated polymers for organic electronics and photovoltaic cell applications. Chem. Mater. 2011;23:733–758.

Lee J, Kalin AJ, Yuan T, Al-Hashimi M, Fang L. Fully conjugated ladder polymers. Chem. Sci. 2017;8:2503–2521. PubMed PMC

Tobe Y. Quinodimethanes incorporated in non-benzenoid aromatic or antiaromatic frameworks. Top. Curr. Chem. 2018;376:12. PubMed

Parkhurst, R. R. & Swager, T. M. in Polyarenes II (eds Jay S. Siegel & Yao-Ting Wu) 141–175 (Springer International Publishing, 2014).

Zeng Z, et al. Pro-aromatic and anti-aromatic π-conjugated molecules: an irresistible wish to be diradicals. Chem. Soc. Rev. 2015;44:6578–6596. PubMed

Frederickson CK, Rose BD, Haley MM. Explorations of the indenofluorenes and expanded quinoidal analogues. Acc. Chem. Res. 2017;50:977–987. PubMed

Mishra S, et al. Tailoring bond topologies in open-shell graphene nanostructures. ACS Nano. 2018;12:11917–11927. PubMed

Liu J, et al. Open-shell nonbenzenoid nanographenes containing two pairs of pentagonal and heptagonal rings. J. Am. Chem. Soc. 2019;141:12011–12020. PubMed

Di Giovannantonio M, et al. On-surface synthesis of antiaromatic and open-shell indeno[2,1-b]fluorene polymers and their lateral fusion into porous ribbons. J. Am. Chem. Soc. 2019;141:12346–12354. PubMed

Mishra S, et al. Topological defect-induced magnetism in a nanographene. J. Am. Chem. Soc. 2020;142:1147–1152. PubMed

Fujii S, et al. Highly-conducting molecular circuits based on antiaromaticity. Nat. Commun. 2017;8:15984–15984. PubMed PMC

Fan Q, Gottfried JM, Zhu J. Surface-catalyzed C–C covalent coupling strategies toward the synthesis of low-dimensional carbon-based nanostructures. Acc. Chem. Res. 2015;48:2484–2494. PubMed

Talirz L, Ruffieux P, Fasel R. On-surface synthesis of atomically precise graphene nanoribbons. Adv. Mater. 2016;28:6222–6231. PubMed

Shen Q, Gao H-Y, Fuchs H. Frontiers of on-surface synthesis: from principles to applications. Nano Today. 2017;13:77–96.

Sun Q, Zhang R, Qiu J, Liu R, Xu W. On-surface synthesis of carbon nanostructures. Adv. Mater. 2018;30:1705630. PubMed

Clair S, de Oteyza DG. Controlling a chemical coupling reaction on a surface: tools and strategies for on-surface synthesis. Chem. Rev. 2019;119:4717–4776. PubMed PMC

Cai J, et al. Graphene nanoribbon heterojunctions. Nat. Nanotechnol. 2014;9:896–900. PubMed

Steiner C, et al. Hierarchical on-surface synthesis and electronic structure of carbonyl-functionalized one- and two-dimensional covalent nanoarchitectures. Nat. Commun. 2017;8:14765. PubMed PMC

Moreno C, et al. Bottom-up synthesis of multifunctional nanoporous graphene. Science. 2018;360:199. PubMed

Sánchez-Sánchez C, et al. On-surface synthesis and characterization of acene-based nanoribbons incorporating four-membered rings. Chem. Eur. J. 2019;25:12074–12082. PubMed

Sánchez-Grande A, et al. On-surface synthesis of ethynylene bridged anthracene polymers. Angew. Chem. Int. Ed. 2019;58:6559–6563. PubMed PMC

Li J, et al. Band depopulation of graphene nanoribbons induced by chemical gating with amino groups. ACS Nano. 2020;14:1895–1901. PubMed

Urgel JI, et al. On-surface synthesis of cumulene-containing polymers via two-step dehalogenative homocoupling of dibromomethylene-functionalized tribenzoazulene. Angew. Chem. Int. Ed. 2020;59:13281–13287. PubMed PMC

Galeotti, G. et al. Synthesis of mesoscale ordered two-dimensional π-conjugated polymers with semiconducting properties. Nat. Mater. 19, 874–880 (2020). PubMed

Cirera B, et al. Tailoring topological order and pi-conjugation to engineer quasi-metallic polymers. Nat. Nanotechnol. 2020;15:421–423. PubMed

Lewis JP, et al. Advances and applications in the FIREBALL ab initio tight-binding molecular-dynamics formalism. Phys. Status Solidi B. 2011;248:1989–2007.

Mendieta-Moreno JI, et al. FIREBALL/AMBER: an efficient local-orbital DFT QM/MM method for biomolecular systems. J. Chem. Theory Comput. 2014;10:2185–2193. PubMed

Vineyard GH. Frequency factors and isotope effects in solid state rate processes. J. Phys. Chem. Solids. 1957;3:121–127.

Crim FF. Chemical dynamics of vibrationally excited molecules: controlling reactions in gases and on surfaces. Proc. Nat. Acad. Sci. USA. 2008;105:12654. PubMed PMC

Guo H, Liu K. Control of chemical reactivity by transition-state and beyond. Chem. Sci. 2016;7:3992–4003. PubMed PMC

Polanyi JC. Concepts in reaction dynamics. Acc. Chem. Res. 1972;5:161–168.

Truhlar DG, Garrett BC, Klippenstein SJ. Current status of transition-state theory. J. Phys. Chem. 1996;100:12771–12800.

Bao JL, Truhlar DG. Variational transition state theory: theoretical framework and recent developments. Chem. Soc. Rev. 2017;46:7548–7596. PubMed

Glidewell C, Lloyd D. MNDO study of bond orders in some conjugated bi- and tri- cyclic hydrocarbons. Tetrahedron. 1984;40:4455–4472.

El Bakouri O, Poater J, Feixas F, Solà M. Exploring the validity of the Glidewell–Lloyd extension of Clar’s π-sextet rule: assessment from polycyclic conjugated hydrocarbons. Theor. Chem. Acc. 2016;135:205.

Gross L, Mohn F, Moll N, Liljeroth P, Meyer G. The chemical structure of a molecule resolved by atomic force microscopy. Science. 2009;325:1110. PubMed

Jelínek P. High resolution SPM imaging of organic molecules with functionalized tips. J. Phys: Condens. Matter. 2017;29:343002. PubMed

Gross L, et al. Bond-order discrimination by atomic force microscopy. Science. 2012;337:1326–1329. PubMed

Neaton JB, Hybertsen MS, Louie SG. Renormalization of molecular electronic levels at metal-molecule interfaces. Phys. Rev. Lett. 2006;97:216405. PubMed

Amy F, Chan C, Kahn A. Polarization at the gold/pentacene interface. Org. Electron. 2005;6:85–91.

Cohen AJ, Mori-Sánchez P, Yang W. Insights into current limitations of density functional theory. Science. 2008;321:792. PubMed

Steckler TT, et al. Very low band gap thiadiazoloquinoxaline donor–acceptor polymers as multi-tool conjugated polymers. J. Am. Chem. Soc. 2014;136:1190–1193. PubMed

Dou L, Liu Y, Hong Z, Li G, Yang Y. Low-bandgap near-IR conjugated polymers/molecules for organic electronics. Chem. Rev. 2015;115:12633–12665. PubMed

Kawabata K, Saito M, Osaka I, Takimiya K. Very small bandgap π-conjugated polymers with extended thienoquinoids. J. Am. Chem. Soc. 2016;138:7725–7732. PubMed

Horcas I, et al. WSxM: a software for scanning probe microscopy and a tool for nanotechnology. Rev. Sci. Instrum. 2007;78:013705. PubMed

Blum V, et al. Ab initio molecular simulations with numeric atom-centered orbitals. Comput. Phys. Commun. 2009;180:2175–2196.

Becke AD. Density-functional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 1998;98:5648.

Hapala P, et al. Mechanism of high-resolution STM/AFM imaging with functionalized tips. Phys. Rev. B. 2014;90:085421. PubMed

Krejčí O, Hapala P, Ondráček M, Jelínek P. Principles and simulations of high-resolution STM imaging with a flexible tip apex. Phys. Rev. B. 2017;95:045407.

Case, D. A. et al. AMBER 2018. University of California, San Francisco (2018).

Heinz H, Lin T-J, Kishore Mishra R, Emami FS. Thermodynamically consistent force fields for the assembly of inorganic, organic, and biological nanostructures: The INTERFACE Force Field. Langmuir. 2013;29:1754–1765. PubMed

Lee C, Yang W, Parr RG. Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Phys. Rev. B. 1988;37:785–789. PubMed

Grimme S, Ehrlich S, Goerigk L. Effect of the damping function in dispersion corrected density functional theory. J. Comput. Chem. 2011;32:1456–1465. PubMed

Basanta, M. A., Dappe, Y. J., Jelínek, P. & Ortega, J. Optimized atomic-like orbitals for first-principles tight-binding molecular dynamics. Comput. Mater. Sci. 39 759–766 (2007).

Kumar S, Rosenberg JM, Bouzida D, Swendsen RH, Kollman PA. The weighted histogram analysis method for free-energy calculations on biomolecules. I. The method. J. Comput. Chem. 1992;13:1011–1021.

Ditchfield R. Self-consistent perturbation theory of diamagnetism. Mol. Phys. 1974;27:789–807.

Chai J-D, Head-Gordon M. Long-range corrected hybrid density functionals with damped atom–atom dispersion corrections. Phys. Chem. Chem. Phys. 2008;10:6615–6620. PubMed

Dunning TH. Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen. J. Chem. Phys. 1989;90:1007–1023.

Gaussian 09, R. D. et al. Gaussian, Inc. (Wallingford, CT, 2013).

On-surface synthesis of non-benzenoid conjugated polymers by selective atomic rearrangement of ethynylarenes

Exploiting Cooperative Catalysis for the On-Surface Synthesis of Linear Heteroaromatic Polymers via Selective C-H Activation