10.1039/b714731g
The research focuses on the development of new strong organic acceptors through the [2 + 2] cycloaddition of tetracyanoethene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) to donor-substituted cyanoalkynes, followed by retro-electrocyclisation. The purpose of this study was to synthesize potent organic acceptors that could rival the electron uptake propensity of benchmark compounds TCNE and TCNQ, which are highly demanded in the fabrication of optical light-emitting diodes (OLEDs) and solar cells. The researchers successfully prepared donor-substituted 1,1,2,4,4-pentacyanobuta-1,3-dienes (PCBDs) and a cyclohexa-2,5-diene-1,4-diylidene-expanded derivative, which exhibited intense bathochromically-shifted intramolecular charge-transfer bands and underwent their first one-electron reductions at potentials similar to those reported for TCNE and TCNQ. The study concluded that these new push-pull chromophores not only matched the electron-accepting power of TCNE and TCNQ but also showed promise for optoelectronic applications.
10.1039/c3nj01290e
The research investigates the reversible iodine absorption properties of the nonporous coordination polymer Cu(TCNQ) (where TCNQ = 7,7,8,8-tetracyanoquinodimethane), with the aim of understanding and controlling its electronic properties through iodine absorption and desorption processes. The study explores both solid-state grinding and liquid-phase reactions to form Cu(TCNQ)I4 from Cu(TCNQ), which is a semiconductor. The key chemicals involved are Cu(TCNQ) in its two polymorphs (phase I and phase II), iodine (I2), and hexane as a solvent for the liquid-phase reaction. The solid-state reaction efficiently produces Cu(TCNQ)I4 for both phases, while the liquid-phase reaction is slower for phase II due to its higher thermodynamic stability. The iodine-containing salt, Cu(TCNQ)I4, has a valence state of [Cu+I(TCNQ0)](I2)1.5, indicating that TCNQ is oxidized to a neutral state upon iodine absorption, and the copper ion coordinates with an iodide anion and neutral TCNQ. The electrical conductivity of the iodine-containing salt is one order lower than that of Cu(TCNQ), demonstrating that the iodine absorption process significantly alters the electronic properties of the material. The study concludes that the iodine absorption-desorption mechanism of Cu(TCNQ) differs from that of alkali-TCNQ salts, with the affinity of I and Cu+ playing a crucial role in the process.
Xn; 
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