Sonogashira coupling in 3D-printed NMR cuvettes: synthesis and properties of arylnaphthylalkynes

3D-Printing has been used to build hollow NMR tube/spinner combinations out of NMR-transparent polyamide. The whole 3D-print has been processed inside a glove box and during pauses of the 3D-printing process, all reactants for the palladium-catalyzed decarboxylative Sonogashira coupling of aryl halides with arylpropiolic acids have been inserted. Within the totally gas tight and pressure resistant tubes, a set of arylnaphthylalkynes has been synthesized and the progress of the reaction has been monitored via NMR spectroscopy. The (nonlinear) optical properties of the push-pull substituted bis(aryl)alkynes have been investigated by fluorescence spectroscopy and DFT calculations. A significant correlation between the intensity of the triple-bond stretching vibration and the calculated first hyperpolarizability is reported.