Retention of Perylene Diimide Optical Properties in Solid-State Materials Through Tethering to Nanodiamonds

two KBr discs and recorded in the 400-4000 cm -1 range at room temperature (with an ATR attachment as appropriate). Ultraviolet-visible spectroscopy (UV/Vis) was carried out using a PerkinElmer Lambda 25 UV/Vis spectrometer in 1 cm length quartz cuvettes with a wavelength range from 190 to 1100 nm. DLS measurements were performed using a Malvern Zetasizer Nano-ZS. ND samples were dispersed in chloroform with ultrasonication for 10 min prior to analysis. Raman and fluorescence spectra were obtained using a HORIBA LabRAM HR Raman microscope (325 or 532 nm laser excitation). Transmission electron microscopy was carried out using JEOL 2100F FEG-TEM with an accelerating voltage of 200 kV (information limit of 0.19 nm). EDX spectroscopy was carried out using an Oxford Instruments 80 mm X-Max system. Samples were prepared for TEM and EDX by casting several drops of methanolic suspension onto copper-grid mounted “holey” carbon films.


Additional characterisation of PDIs
Single crystal structure of 1a.Single crystal X-ray diffraction experiments were performed on a XtalLAB PRO MM007, PILATUS3 R 200K diffractometer at 120 K using monochromated Cu Ka radiation (l = 1.5418Å).The structures were solved by direct methods using SHELXS or SHELXT S9 and refined with SHELXL S10 using a least squares method.OLEX2 software was used as the solution, refinement and analysis program.S11 All hydrogen atoms were placed in geometrically calculated positions; non-hydrogen atoms were refined with anisotropic displacement parameters.In specific cases geometric restraints were applied.Details of dealing with disorder and other refinement are described in the corresponding, deposited cif, CCDC 2085715 (1a).Disordered solvent molecules could not be sensibly modelled to give convergence and the data was treated with PLATON SQUEEZE, S12 which gave an estimate of 182 electrons per cell, corresponding to approximately 3 molecules of chloroform per unit.(orange).The peak at ~1315 cm -1 in both spectra is consistent with the triply degenerate zone-centre optical phonon with F2g symmetry found in diamond.The peak at ~1597 cm -1 is the characteristic G-band associated with sp 2 -hybridised carbon nanostructures.The peak at ~1630 cm -1 is a combination of an O-H bend and C=C stretching vibration; it reduces in intensity (relative to the G-band) after oxidation and suggests that (i) non-carboxylic acid functional groups were removed or converted to acid groups during acid treatment, and (ii) that sp 2 -hybridised carbon has not been lost during this treatment.Fluorescence spectroscopy analysis of PDIs and ND-PDIs

Figure S1 .
Figure S1.Views of the single crystal X-ray structure of 1a.(a) The structure of 1a confirming the 1,7-subsitution pattern (carbon -grey; oxygen -red; nitrogen -blue; hydrogen -white); (b and c) stacking of two adjacent molecules of 1a in the solid-state structure, (b) view parallel to stacking and (c) view perpendicular to stacking.Adjacent molecules are shown in red and blue to aid the reader.

Figure S2 .
Figure S2.The 325 nm Raman spectra of pristine ND (blue) and oxidised nanodiamonds ND-COOH(orange).The peak at ~1315 cm -1 in both spectra is consistent with the triply degenerate zone-centre optical phonon with F2g symmetry found in diamond.The peak at ~1597 cm -1 is the characteristic G-band associated with sp 2 -hybridised carbon nanostructures.The peak at ~1630 cm -1 is a combination of an O-H bend and C=C stretching vibration; it reduces in intensity (relative to the G-band) after oxidation and suggests that (i) non-carboxylic acid functional groups were removed or converted to acid groups during acid treatment, and (ii) that sp 2 -hybridised carbon has not been lost during this treatment.

Figure S3 .
Figure S3.IR spectra of ND-COOH (black), ND-1a (green) and ND-1b (blue).The observation of a broad peak at 3415 cm -1 is consistent with an OH stretching mode of the carboxylic acid groups in ND-COOH.Its presence subsequent to reaction with PDI can be rationalised by residual carboxylic acids in the ND-PDI species, or potentially unreacted pendent alcohols in ND-1aor ND-1b.

Figure S5 .Figure S6 .
Figure S5.EDX spectrum of ND-COOH.Note: Cu peaks are due to the copper mesh of the TEM grid.

Figure S7 .
Figure S7.(a) The structure of the 2,6-diisopropylphenyl-substituted PDI (3), chosen for control measurements owing to its inability to form ester linkages with surface functional groups of ND-COOH.(b) Normalised fluorescence spectra of 3 as solid powder, in acetonitrile solution and as mechanical mixture with ND-COOH (powders ground in a 1:1 mass ratio for 5 minutes in a pestle and mortar), indicating that the mechanical mixture more closely resembles the parent PDI powder than the solution.(c) An optical image of the mechanical mixture of ND-COOH and 3 and corresponding fluorescence maps (20x20 µm in 1 µm steps) displaying (d) the intensity (as peak height) and (e) the position of the emission maximum.The optical micrograph indicates that the mixed powder contains micron-sized crystalline domains of the two components, which can be readily discriminated by their peak intensity in (d).However, the relative position of the emission maximum (e)