The influence of pyrrole linked to the π-conjugated polyene on crystal characteristics and polymorphism

Enolizable Alkylidene Heterocyclic and Carbocyclic Carbonyl Systems­: Valuable Vinylogous Donor Substrates in Synthesis

“…This substrate, indeed, has been mainly and widely exploited for more than 15 years in the context of aldol condensation chemistry using a plethora of aromatic aldehydes as acceptor components. [107][108][109][110][111][112][113][114][115][116][117][118][119] One of the first reports dates back to 2000, when 120a was coupled to p-aminobenzaldehydes 38 under basic treatment 107 to obtain highly conjugated achiral products 193 (Scheme 66).…”

“…These characteristics confer those physical requisites (including high dipole moment and polarizability anisotropy, reduced dielectric strength and reduced tendency to crystallize) that are key for their use as chromophoric dopants in photorefractive polymer composites, stimulusresponsive dyes, or fluorescent biocompatible probe. [108][109][110][111][112][113][114][115][116][117][118][119] Finally, the vinylogous aldol condensation of isophorone-derived 120a with pyrazole 194 (Scheme 67) was reported in 2012 120 as the starting reaction in a multi-step sequence directed toward the synthesis and antimicrobial evaluation of benzo [b]thiophene-β-lactam congeners. The dicyanoolefin moiety within product 195 served then to construct the fused thiophene heterocycle in the advanced intermediate 196 and in the β-lactam targets (not shown).…”

Effect of ionic organic additives for the growth of polyene crystals synthesized by Knoevenagel condensations

“…For organic single crystals grown from such molecules, the impurities can affect several important physical properties including the growth process. [16][17][18] The impurities resulting from synthesis can act as undesired additives and result in a difficult control of the growth morphology, nucleation, single crystallinity and polymorphism. [16][17][18] Additives can also affect the optical quality including the surface quality.…”

“…[16][17][18] The impurities resulting from synthesis can act as undesired additives and result in a difficult control of the growth morphology, nucleation, single crystallinity and polymorphism. [16][17][18] Additives can also affect the optical quality including the surface quality. Therefore, without hard and time-consuming purification processes, development of an appropriate crystal growth method for bulk organic single crystals or thin films with high optical quality and controlled crystal characteristics is usually impossible.…”

Pyrrolic molecular rotors acting as viscosity sensors with high fluorescence contrast

“…11,14 The conformation of the two rotational isomers(R-and L-isomers) is shown in Scheme S1 in the ESI. † The two rotational isomers might present different rotation efficiencies, resulting in bi-exponential fluorescence decay profiles in high viscosity ranges.…”