Arx 250

All solvents and chemicals were purchased from SDS and Aldrich, respectively. DMF, MeOH and CH₃CN were dried using standard. ¹H NMR and ¹³C NMR spectra were recorded on Bruker ARX-250 and Bruker Avance-500 spectrometers, respectively, and chemical shifts were reported in ppm downfield from TMS. IR spectra were obtained with a Perkin-Elmer Spectrum One FT-IR spectrometer equivuipped with a MIRacle^TM single reflection horizontal ATR unit (germanium crystal). Electrospray ionization (ESI) mass spectrometry analyses and HRMS were obtained using Thermo Finnigan LCQ Advantage spectrometer. The elemental analyses were carried out by the mass spectrometry and microanalysis services in Gif-sur-Yvette (CNRS).

Analyses by thin layer chromatography (TLC) were performed on a Merck silica-gel 60 F₂₅₄ (Darmstadt, Germany), and TLC plaques were visualized by UV-lamp at wavelengths of 254 and 365 nm. Unless otherwise noted, for column chromatography Merck silica-gel 60 (40–63 μm or 63–200 μm) was used. For gel-permeation or size-exclusion column chromatography Bio-Beads S-X1 from Bio-Rad Laboratories (Richmond, CA, USA) were used in toluene.
The NMR spectra were recorded on Bruker spectrometers: Avance-300, ARX-250 and Avance 500 (Billerica, MA, USA) at the Laboratoire de Chimie de Coordination, Toulouse, France. UV-visible spectra were obtained using a Perkin Elmer Lambda 25 (Waltham, MA, USA) or on a Varian Cary 100 Bio (Palo Alto, CA, USA) spectrophotometer in dichloromethane. Fluorescence spectra were recorded on a Perkin Elmer LS 55 spectrometer in dichloromethane at the Laboratoire de Chimie de Coordination in Toulouse, France. Elemental analyses were carried out by the Service de microanalyse at the Laboratoire de Chimie de Coordination in Toulouse, France.
The syntheses of monomer 8 and dimer 5 are summarized in Scheme 1 and Scheme 2 and described in the following sections.