**2. Materials and Methods**

In the present work, we present tolane structures that form crystalline thin films and assess their MO activity by FR spectroscopy (Figure 1).

**Figure 1.** Tolanes (**1**–**3**) and *N*-Hetero-tolane derivatives **4** and **5**.

The diphenyltolanes **1**–**3** present a conventional donor-π-acceptor system. Compounds **2** and **3** have been studied previously for their second-order NLO properties [19].
