**Maarten Eerdekens 1, Ismael López-Duarte 2, Gunther Hennrich 2,\* and Thierry Verbiest 1,\***


Received: 11 September 2019; Accepted: 12 October 2019; Published: 16 October 2019

**Abstract:** We present organic, diamagnetic materials based on structurally simple (hetero-)tolane derivatives. They form crystalline thin-film aggregates that are suitable for Faraday rotation (FR) spectroscopy. The resulting new materials are characterized appropriately by common spectroscopic (NMR, UV-Vis), microscopy (POM), and XRD techniques. The spectroscopic studies give extremely high FR activities, thus making these materials promising candidates for future practical applications. Other than a proper explanation, we insist on the complexity of designing efficient FR materials starting from single molecules.

**Keywords:** faraday rotation; thin films; magneto-optics; organic material; tolane derivatives
