On-surface derivatisation of aromatic molecules on graphene: the importance of packing density

Abstract

We present the production of high packing density molecular monolayers on graphene through a modified transfer process and demonstrate their increased stability during derivatisation.

Isomerically Pure Star‐Shaped Triphenylene–Perylene Hybrids Involving Highly Extended π‐Conjugation

“…Furthermore, we inspected the samples by atomic force microscopy (AFM), which revealed the presence of characteristic smooth graphene surfaces with the presence of wrinkles, in which thin layers of 9 isomers approximately 3 nm thick were clearly observed, in excellent agreement with related water‐soluble PDI thicknesses determined by spectroscopic ellipsometry . The rough mean square values (RMS) of the functionalized surfaces were 1.6±0.7 and 0.9±0.2 for the C 3 h and C s isomers, respectively, indicative of a very homogeneous and smooth surface (Figure d).…”

“…[58] Furthermore, we inspected the samples by atomic force microscopy (AFM), which revealed the presence of characteristic smooth graphene surfaces with the presence of wrinkles, in which thin layers of 9 isomersa pproximately 3nmt hick were clearlyo bserved, in excellent agreement with related watersoluble PDI thicknesses determined by spectroscopice llipsometry. [57] The rough mean square values (RMS) of the functionalized surfaces were 1.6 AE 0.7 and0 .9 AE 0.2 fort he C 3h and C s isomers, respectively,i ndicative of av ery homogeneousa nd smooth surface (Figure 6d). Additionally,w eh ave performed Raman mappings with an increased resolution of 200 nm, demonstrating that the covering is completely homogeneous and is not dependento nt he corrugations and wrinkles of the graphene substrate ( Figures S14-15 in the Supporting Information).…”

“…1351 cm À1 ) and the Gp eak of the graphene substrate can be efficiently used as an estimation of the packingd ensity. [56,57] Indeed, both isomerse xhibitedv ery homogeneous mean PDI n Ag /G ratios of 1.03 and 0.93 (full width at half maximum (FWHM) = 0.10 and 0.11) for the C 3h and C s isomers, respectively,i ndicative of a high packing density (Figure6b). Interestingly,t hanks to the profoundquenching of the fluorescence, it was possible to distinguish both isomersw hen analyzing the PDI-related bands centered at approximately 1351, 1403, 1447, and 1548 cm À1 , showingameasurable shift to lower frequencies( mode softening) of all the Ramanm odes for the C s with respectt ot he C 3h isomer in the 1.5-6.7 cm À1 range (Figure 6c).…”

“…As recently reported by Duesberg and co‐workers, the ratio between the ν Ag (ca. 1351 cm −1 ) and the G peak of the graphene substrate can be efficiently used as an estimation of the packing density . Indeed, both isomers exhibited very homogeneous mean PDI ν Ag /G ratios of 1.03 and 0.93 (full width at half maximum (FWHM)=0.10 and 0.11) for the C 3 h and C s isomers, respectively, indicative of a high packing density (Figure b).…”

Highly Selective Non‐Covalent On‐Chip Functionalization of Layered Materials

“…The PBI was shown to adsorb as a SAM on graphene with the short core axis perpendicular to the surface. [ 36,37 ] Commonly the interaction between an electron‐poor PBI derivative and the π‐system of the graphitic material is expected to lead to a face‐on attachment (with the molecular core plane parallel to the π‐surface (π‐π stacking). [ 34,38 ] Nevertheless, other influences, like the molecular design and its pre‐orientation and assembly in solution may alter the arrangement on a surface.…”