2-[5-(2-Pyridyl)-1,2,4-triazol-3-yl]phenol 7,7,8,8-tetracyanoquinodimethane, PTP-TCNQ, synthesis, structure and physical properties

A new charge-transfer complex PTP-TCNQ (PTP=2[5-(2-pyridyl)-1,2,4-triazol-3-yl]phenol, TCNQ=1,1,8,8-tetracyanoquinodimethane) has been synthesized and crystallized in the form of black needles. Single crystal X-ray diffraction shows that the solid contains stacks of alternating PTP and TCNQ molecules. The localized charge-transfer responsible for the colour of the material is confirmed by low conductivity of the pelletised powder form (<10⁻⁶ Ω⁻¹ cm⁻¹ at 298 K). The complex is paramagnetic: this is interpreted as a free electron localization on the acceptor molecule of the complex. The mid-IR region of the spectrum of the material confirms the presence of a charge-transfer interaction.