1 Supporting Information for A Straightforward Modular Approach to NLO-active β-Amino Vinyl Nitrothiophenes Thomas J. J. Müller,* Jan P. Robert, Elmar Schmälzlin, Christoph Bräuchle, and Klaus Meerholz General Considerations. Reagents and solvents were purchased reagent grade and used without further purification. Toluene and THF were dried and distilled according to standard procedures. 1 The 2-bromo-5-nitrothiophene was prepared according to literature. 2 – Column chromatography: silica gel 60 (Merck, Darmstadt), mesh 70–230. TLC: silica gel plates (60 F 254 Merck, Darmstadt). Melting points (uncorrected values): Büchi B-540. – 1 H and 13 C NMR spectra: Bruker ARX 300, Varian VXR 400S [D 6 ]DMSO. The assignments of quaternary C, CH, CH 2 and CH 3 has been made by using DEPT spectra. – IR: Perkin Elmer Lambda 3. – UV/vis: Perkin Elmer Models Lambda 16. - Fluorescence spectra: Perkin-Elmer LS 50 B (irradiation at approximately 20 nm less in energy than the longest wave length absorption maximum). - MS: Finnigan MAT 90 and MAT 95 Q. – Elemental analysis were carried out in the Microanalytical Laboratory of the Institut für Organische Chemie, Ludwig- Maximilians-Universität München. HRS-Measurements of the Hyperpolarizabilities of the Compounds 3a and 3b. The HRS experiments were carried out in chloroform. The HRS cell consisted of a 12 cm long glass tube of 1 cm diameter filled with the solution under investigation. A tunable optical parametric oscillator (OPO)-based HRS apparatus was used for the measurements at 1500 nm. 3 To determine the β-values, the external reference method was used. Here, the intensity of the second harmonic I(2ω) is measured for a dilution series of the chromophore under