Four Molecular Superconductors Isolated as Nanoparticles

Abstract

Upon reduction of a 1H‐cyclobuta[de]naphthalene‐4,5‐diylbis(diarylmethylium) species, a new CC bond is formed between the Cα and Cortho atoms of the two chromophores, which presents an unprecedented coupling pattern for the dimerization of two trityl units. By attaching an annulated cyclobutane ring at the opposite peri position of the naphthalene core, the distance between the Cα carbon atoms was elongated beyond the limit of σ‐bond formation through “scissor effects”. The suppression of CαCα bond formation, which would lead to hexaphenylethane‐type compounds, is key to the first successful isolation of the α,o‐adducts. The 5‐diarylmethylene‐6‐triarylmethyl‐1,3‐cyclohexadiene unit in the α,o‐adducts is stable, and isomerization of the cyclohexadiene unit into an aromatic system was not observed. The newly formed CαCortho bond was cleaved upon two‐electron oxidation to regenerate the dicationic dye.

Spin density wave and superconducting properties of nanoparticle organic conductor assemblies

“…Additional refinements of the synthesis conditions have produced a number of DA organic superconductors where strong correlations between the spectroscopic and crystallographic properties of the bulk materials and the nanoparticles have been established 10 . In light of these advances, the main purpose of the present work is to identify the low temperature thermodynamic ground states of the nanoparticle species.…”

“…1. High resolution transmission electron microscope (HR-TEM) studies 10 show that single crystal constituent nanoparticles of approximately 3 to 5 nm in size (see Supplementary Figure 1 11 ) make up nanoparticles that TEM images show are on average about 10 times larger (e.g. average cluster size of 34 nm).…”

Molecular conductors as nanoparticles in the presence of long-chain alkyl imidazolium salts or amphiphilic molecules

“…This is also accompanied by a sharp exothermic peak on the Heat Flow curve (onset point 232.9 °C, peak maxima 235.8 °C and heat of decomposition 160 J.g −1 ), which is due to a fast degradation reaction. Between 273.9 and 437.6 °C an additional amount of 13.2%, while in the 440.5 and 709.4 °C region 16.7% is lost. In the last step the speed of the mass loss (on the DTG curve) decreases, between 712.5 and 1,013.7 °C 13.2% of the starting material is lost.…”

“…Furthermore, we have recently published the preparation of (TMTSF) 2 ClO 4 nanocrystals (TMTSF: tetramethyltetraselenafulvalene) using the electrocrystallisation technique in the presence of N-octylfurfuryl-imine ( Fig. 2), acting as a growth controlling agent [16]. Contrary to what observed in TTFTCNQ/octylamine nanoparticles, the Noctylfurfuryl-imine molecule did not react with the TMTSF molecule but was presumably associated to the TMTSF through -overlap via the furfuryl group during the growth whereas the C 8 chain prevented nanocrystals from aggregation.…”

“…Contrary to what observed in TTFTCNQ/octylamine nanoparticles, the Noctylfurfuryl-imine molecule did not react with the TMTSF molecule but was presumably associated to the TMTSF through -overlap via the furfuryl group during the growth whereas the C 8 chain prevented nanocrystals from aggregation. High resolution transmission electron micrographs also evidenced that nanocrystals (sizes in the 20−70 nm range) were actually made of aggregated individual 2−6 nm nanoparticles [16]. In order to obtain nanoparticles exhibiting mean diameters as small as 10 nm, we have evaluated, in the present paper, the use of (i) a bulky imidazolium cation, i.e., 1-hexadecyl-3-methylimidazolium (HDMIM + , Fig.…”