Bluish Hydrochromic Naphthalenediimide Salt: Change of Hydrogen-bond Interactions as the New Mechanism of Vapochromism

Deprotonation‐Induced Color Modulation in N,N′‐Dihydroxynaphthalenediimide‐Based Organic Crystals

“…In this crystal, Bu 4 N + ions exist between two NDI cores as shown in Figure 1d, limiting the π‐stacked surface only to one of the imide‐carbonyl groups. This structural feature is similar to the previously reported dianionic salt, (Bu 4 N) 2 (O−NDI−O) ⋅ 6H 2 O [16] . The isolation of this crystals was confirmed by the powder X‐ray diffraction (PXRD) pattern (Figure S4) and the elemental analysis.…”

“…This structural feature is similar to the previously reported dianionic salt, (Bu 4 N) 2 (OÀ NDIÀ O) • 6H 2 O. [16] The isolation of this crystals was confirmed by the powder X-ray diffraction (PXRD) pattern (Figure S4) and the elemental analysis.…”

“…We also reported an organic salt, (Bu 4 N) 2 (OÀ NDIÀ O) • 6H 2 O, as uncommon bluish solid. [16] In this crystal, (OÀ NDIÀ O) 2À ions are isolated from each other by Bu 4 N + ions unlike other reported compounds with π-stacked arrays. On the basis of the isolated crystal structure and DFT calculations, we concluded that the (OÀ NDIÀ O) 2À ion intrinsically shows bluish color.…”

Proton–electron-coupled functionalities of conductivity, magnetism, and optical properties in molecular crystals

“…[94][95][96][97][98][99][100][101][102] Although many vapochromic materials bearing H-bonds have been reported to date, they have also been understood merely by structural changes. 62,63,[103][104][105][106][107][108][109][110][111][112][113][114][115][116] The mechanisms reported thus far have only considered the electronic states of an isolated complex, ignoring intermolecular interactions. Thus, to the best of our knowledge, there have been no reports on vapochromism based only on proton-electron coupling in the solid state.…”

An electrically conductive metallocycle: densely packed molecular hexagons with π-stacked radicals

“…It has been widely used for the syntheses of organic conductors 28 and, more recently, porous molecular conductors (PMCs), 29,30 which are porous crystals consisting of linear coordination polymers with a conductive π-stacked array of N , N ′-di(4-pyridyl)-1,4,5,8-naphthalenetetra-carboxdiimide (NDI-py) linkers. The NDI core is a well-known electron acceptor used in various research fields 31 such as self-assembly, 32 molecule sensors 33 and molecular electronics, 34 whereas its application in intrinsic electron conductors is still in the early stage of development.…”