Spectroscopic Characterization of Pyridine Derivatives

¹H, ¹³C{¹H} and 2D NMR spectra were recorded on a Bruker Avance iii-500 spectrometer (Bruker BioSpin AG, Fällanden, Switzerland) at 298 K. The ¹H and ¹³C NMR chemical shifts were referenced with respect to residual solvent peaks (δ TMS = 0). A Shimadzu LCMS-2020 instrument (Shimadzu Schweiz GmbH, 4153 Reinach, Switzerland) was used to record electrospray ionization (ESI) mass spectra. A PerkinElmer UATR Two instrument (PerkinElmer, 8603 Schwerzenbach, Switzerland) was used to record FT-infrared (IR) spectra, and Shimadzu UV2600 (Shimadzu Schweiz GmbH, 4153 Reinach, Switzerland) or Cary 5000 (Agilent Technologies AG, 4052 Basel, Switzerland) spectrophotometers were used to record absorption spectra. 3-Acetylpyridine and 4-hydroxybenzaldehyde were purchased from Acros Organics (Fisher Scientific AG, 4153 Reinach, Switzerland), rac-4-(butan-2-yloxy)benzaldehyde, 4-(2-methylpropoxy)benzaldehyde and 4-(tert-butoxy)benzaldehyde from Fluorochem (Chemie Brunschwig AG, 4052 Basel, Switzerland), 1-bromo-2-methylpropane from Sigma Aldrich (Chemie Brunschwig AG, 4052 Basel, Switzerland), and were used as received. 4′-(4-Hydroxyphenyl)-3,2′:6′,3″-terpyridine was prepared as previously described [6 (link)].