This study highlights a novel strategy for tuning the electrical conductance of single molecules by cross linking the molecules to form a dimer.

Transcribing quantum effects from lower to higher dimensions is a complex yet intriguing area of research.

Correction for 'Tuning quantum interference through molecular junctions formed from cross-linked OPE-3 dimers' by Bashayr Alanazi et al., J. Mater. Chem. C, 2024, 12, 6905-6910, https://doi.org/10.1039/D4TC00611A.

Correction for ‘Tuning quantum interference through molecular junctions formed from cross-linked OPE-3 dimers’ by Bashayr Alanazi et al. , J. Mater. Chem. C , 2024, 12 , 6905–6910, https://doi.org/10.1039/D4TC00611A.

Organic thin films composed of highly ordered molecular arrays hold tremendous potential for thermoelectric energy harvesting. In comparison to metal-thiolate arrays formed through covalent bonding, molecular arrays bound to graphene substrates via non-covalent interactions exhibit superior thermoelectric behavior. Recent studies have explored the thermoelectric properties of non-conjugated junctions utilizing graphene as a substrate. However, for energy-harvesting purposes, conjugated oligo-aromatic molecules with narrower HOMO-LUMO gaps are more desirable. The step-wise assembly strategy, which involves using a zinc-centered porphyrin to form a footpad first and subsequently binding the molecular backbones to the regularly arranged zinc centers in the footpad, has been reported as an effective approach for growing conjugated molecular backbone arrays, with minimal intermolecular effects on various types of substrates. In this study, we employ this strategy to fabricate aromatic molecular arrays on graphene substrates. Initially, a zinc-centered porphyrin layer is immobilized onto the graphene substrate through pi-pi stacking interactions. Subsequently, a conjugated pyridine backbone is coordinated to the zinc tetraphenylporphyrin (ZnTPP). Due to the substantial footprint of ZnTPP, this sequential assembly method effectively separates the molecular backbones and prevents smearing of the density of states arising from intermolecular interactions. Consequently, a significant enhancement in thermopower is achieved. Our findings present a novel approach for designing high-efficiency thermoelectric materials, resulting in a Seebeck coefficient of approximately 51 mu V K-1. This value surpasses the majority of reported Seebeck coefficients for organic molecular junctions.

Molecular radicals such as nitric oxide (NO) play a role in numerous important biological processes. NO, however, is inherently unstable, and there is considerable interest in stable radicals with analogous behaviour, such as (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), and their potential as biologically active surface coatings. Here we show that it is possible to grow stable TEMPO monolayers with an ordered arrangement and specific orientation of the nitroxide group. A combination of high-resolution atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations reveal that strong dipole-dipole interactions between neighbouring TEMPO molecules determine their orientation, resulting in an anti-parallel arrangement with upwards and downwards facing nitroxide groups. Surface coating is made possible using plasma polymerisation, a surface molecular engineering technique suitable for growing functional coatings of highly stable organic molecules. Typically, plasma polymerisation is considered a surface-independent process, with the plasma power and pressure dominating the deposited film's properties. We therefore test this assumption and its impact on TEMPO layers by studying initial stage growth on multiple material surfaces. We show that whilst plasma polymer growth creates ordered layers on gold and graphite surfaces, there is substantial substrate-dependence with less ordered growth on other materials up to a film thickness of 30 nm, suggesting variation in molecular packing and retention. Beyond that thickness, films convergence to a flat, uniform, surface-agnostic structure. These findings establish the utility of plasma polymerisation as a method for ordered growth and demonstrate the ability to direct the orientation of TEMPO molecules and NO free radicals within a thin film.