1D Coordination π–d Conjugated Polymers with Distinct Structures Defined by the Choice of the Transition Metal: Towards a New Class of Antiaromatic Macrocycles

Abstract

Recently p-d conjugated coordination polymers have received alot of attention owing to their unique material properties,although synthesis of long and defect-free polymers remains challenging. Herein we introduce an ovel on-surface synthesis of coordination polymers with quinoidal ligands under ultra-high vacuum conditions,whiche nables formation of flexible coordination polymers with lengths up to hundreds of nanometers.M oreover,t his procedure allows the incorporation of different transition-metal atoms with four-ortwo-fold coordination. Remarkably,t he twofold coordination mode revealed the formation of wires constituted by (electronically) independent 12-membered antiaromatic macrocycles linked together through two CÀCs ingle bonds.

Significance of nuclear quantum effects in hydrogen bonded molecular chains

“…However, this scenario can be ruled out by several observations. Namely, XPS measurements of DABQDI molecules deposited on Au(111) at room temperature show in N1s region two distinct components corresponding to both -NH 2 and -NH groups (see Figure S3 in Santhini et al 26 ). Moreover, in very rare instances we observe the formation of short defective chains (see Extended Data Fig.…”

On-Surface Synthesis: A New Route Realizing Single-Layer Conjugated Metal–Organic Structures

“…Benzene-based molecules have been used to react with metal atoms (Scheme 2). [31][32][33][34][35][36][37][38] All these molecules are based on a phenyl ring with four radicals: i) a zwitterionic quinone (ZQ) functionalized by 2 amine groups and two carboxylic groups, ii) tetrahydroxy benzene (THB) and iii) 2,5 diamino-1,4benzoquinonediimines (2HQDI). The formation of 1D-cMOFs from these molecules proceeds by successive deprotonation/metalation steps in which two covalent bonds and two coordinative bonds are formed between the metal center and two adjacent molecules.…”

“…31 1D-cMOF (Product 3) comprising 2HQDI and metal atoms (M = Cr, Fe, Co, Ni) are formed on Au(111) and Cu(111). 38 A combination of XPS, STM, nc-AFM, and DFT calculations was used to characterize in (Figure 1j), demonstrating that all metal atoms adopt a fourfold coordination motif with the nitrogen atoms after dehydrogenation of the 2HQDI molecules providing a full delocalization of the π-d electron system over the entire 1D-cMOF. In contrast, complexation between Cu adatoms and 2HDQI molecules on Cu(111), a different configuration of the metal is obtained, in which 2-fold coordination of Cu atoms preventing the full delocalization of the electron density over the nanowire.…”

“…In contrast, complexation between Cu adatoms and 2HDQI molecules on Cu(111), a different configuration of the metal is obtained, in which 2-fold coordination of Cu atoms preventing the full delocalization of the electron density over the nanowire. 38 Transition metal complexes with 4 to 7 d electrons can adopt different spin configurations either high-spin, intermediate-spin and low-spin depending on ligand field splitting, and SCO has been observed under external stimuli such as light, pressure temperature or electric field. 48 The on-surface synthesis of 1D-cMOF has allowed a description and manipulation of individual spin state at the atomic level.…”