Photophysical and crystallographic study of three integrated pyrazolo[1,5-a]pyrimidine–triphenylamine systems

Pyrazolo[1,5-a]pyrimidines-based fluorophores: a comprehensive theoretical-experimental study

“…Along this direction, we recently demonstrated the improvement in the photophysical properties with the incorporation of a conjugated substituent at position 2. 31…”

“…It is worth noting that in the donor-acceptor molecular systems, the microcrystalline arrangement allows an intermolecular uorescence quenching due to the antiparallel organization of the molecules. 31,41,42 Likewise, in N-heterocyclic compounds that lack strong electrostatic interactions due to the absence of polar functional groups, the van der Waals forces are mainly responsible for their formation in the solid-state and apparently, these forces are improved by the presence of simple aryl groups at the ring periphery. The supramolecular assembly can be promoted by the molecular chain formations having aryl groups or fused heterocyclic moieties in a strategic disposition of p/p stacking and C-H/p (or C-H/N) interactions.…”

“…The supramolecular assembly can be promoted by the molecular chain formations having aryl groups or fused heterocyclic moieties in a strategic disposition of p/p stacking and C-H/p (or C-H/N) interactions. 31,[43][44][45][46][47] Some haloaryl substituents play a crucial role in molecular packing and the photophysical properties of their derivatives, such as the 2,4-dichlorophenyl (2,4-Cl 2 Ph) group. 44,45 In this context and as expected, probes 4c, 4f and 4g showed lower emission intensities with respect to those found in the rest of the series (intensity in 4b > 4d > 4e > 4a), since they bear bulky groups that disfavor both good packing and uorescence intensity (Fig.…”

Functional Pyrazolo[1,5-a]pyrimidines: Current Approaches in Synthetic Transformations and Uses As an Antitumor Scaffold

“…Conversely, if the 1,3-biselectrophilic system is a β-enaminone moiety, it enhances the reactivity or performance compared to 1,3-dicarbonyl compounds [ 1 , 37 , 38 ]. Portilla and co-workers employed diverse β-enaminone derivatives 19a–l following a highly efficient methodology under MW irradiation, obtaining various 2,7-disubstituted products 20a–ac in high yields ( Scheme 5 ) [ 17 , 18 , 21 , 38 ]. The regioselectivity of the reaction can be controlled using the dimethylamino leaving group, where the initial condensation proceeds via an addition–elimination mechanism (aza-Michael type), thus bonding the NH 2 -group of the starting aminopyrazole with the Cβ of 19a–l [ 37 ].…”

“…Furthermore, the biocompatibility and lower toxicity levels of PP derivatives have led them to reach commercial molecules, for instance, Indiplon, Lorediplon, Zaleplon, Dorsomorphin, Reversan, Pyrazophos, Presatovir, and Anagliptin ( Figure 2 ) [ 1 , 2 , 3 , 4 , 5 ]. In recent years, this molecular motif has been a focus of study for promising new applications related to materials sciences [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ], due to its exceptional photophysical properties as an emergent fluorophore [ 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Likewise, the tendency of pyrazolo[1,5- a ]pyrimidine derivatives to form crystals with notable conformational and supramolecular phenomena [ 17 , 22 , 23 ] could amplify their applications towards the solid-state.…”