Folded conformations due to arene interactions in dissymmetric and symmetric butylidene-linker models based on pyrazolo[3,4-d]pyrimidine, purine and 7-deazapurine

Abstract

The butylidene-linker models 1-[2-(2,6-dimethylsulfanyl-9H-purin-9-yl)-2-methylidenepropyl]-4,6-bis(methylsulfanyl)-1H-pyrazolo[3,4-d]pyrimidine, C18H20N8S4, (XI), 7,7'-(2-methylidenepropane-1,3-diyl)bis[3-methyl-2-methylsulfanyl-3H-pyrrolo[2,3-d]pyrimidin-4(7H)-one], C20H22N6O2S2, (XIV), and 7-[2-(4,6-dimethylsulfanyl-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-2-methylidenepropyl]-3-methyl-2-methylsulfanyl-3H-pyrrolo[2,3-d]pyrimidin-4(7H)-one, C19H21N7OS3, (XV), show folded conformations in solution, as shown by (1)H NMR analysis. This folding carries over to the crystalline state. Intramolecular π-π interactions are observed in all three compounds, but only (XIV) shows additional intramolecular C-H···π interactions in the solid state. As far as can be established, this is the first report incorporating the pyrrolo[2,3-d]pyrimidine nucleus for such a study. In addition to the π-π interactions, the crystal structures are also stabilized by other weak intermolecular C-H···S/N/O and/or S···N/S interactions.

Highly Efficient Perovskite Solar Cells Employing an Easily Attainable Bifluorenylidene‐Based Hole‐Transporting Material

“…Similar to that of spiro‐OMeTAD, due to the highly sterically hindered geometry, no close face to face overlap is observed. However, the small π⋅⋅⋅π distance and short C⋅⋅⋅O contacts are expected to facilitate the facile establishment of highly efficient charge transport channel.…”

Two‐Dimensional Calix[4]arene‐based Metal–Organic Coordination Networks of Tunable Crystallinity

“…Thed istance between the latter, upright oriented arene rings of two adjacent molecules is 3.9 ,c onsistent with am oderate p-p stacking interaction energy. [18,19] This coordination unit also implies that two adjacent calixarene molecules in the flattened-arene-Cu-flattened-arene direction (named x direction in Figure 6a)a re slightly tilted, with an angle out of the HOPG plan. This is expected to cause the formation of corrugations in the same axis and is consistent with the crystalline stripes shown in the AFM data.…”

Highly Efficient Perovskite Solar Cells Employing an Easily Attainable Bifluorenylidene‐Based Hole‐Transporting Material

“…In one unit cell, four independent molecules the crystal lattice stacked in ah ighly slipped fashion (Figure 1c,d) through p···p,C ···C and C···O short contacts as well as CH/ p (CH/O) hydrogen bonds.Eight fluorenes are found to have three different types of orientation. However,the small p···p distance [20] and short C···O contacts are expected to facilitate the facile establishment of highly efficient charge transport channel. Similar to that of spiro-OMeTAD,d ue to the highly sterically hindered geometry,n oc lose face to face overlap is observed.…”

“…Similar to that of spiro-OMeTAD,d ue to the highly sterically hindered geometry,n oc lose face to face overlap is observed. However,the small p···p distance [20] and short C···O contacts are expected to facilitate the facile establishment of highly efficient charge transport channel.…”