T uning and controlling the photophysical properties of luminescent materials by changing environmental factors has been intensively studied in terms of fundamental research and practical applications in the fields of sensing, memories, detection, and display devices. [1][2][3][4][5][6][7][8][9] Particularly, stimuli-responsive fluorescence switching, such as piezochromism, vapochromism, and thermo-and acid-dependent luminescence of smart luminescent materials, has received unprecedented attentions. [10][11][12][13][14][15] Piezochromic luminescence has been obtained by changing molecular packing modes of solid materials at different phases through grinding and heating treatments. [16][17][18][19][20][21] Vapochromic organic materials were designed in an effective strategy of tuning weak intermolecular interactions such as π-stacking and hydrogen bonding. 22 Thermo-and acid-dependent luminescent materials also owned pronounced molecular structures, whose conformations or frontier molecular orbital (FMO) could be affected by thermo, acid, or base. 23 However, reports on multistimuli-responsive fluorescence switching of one chromophore are quite rare, 24,25 which is due to the lack of clear guidelines for the design of molecular structure synchronously possessing all the features of different smart materials.Herein, we synthesized an electron donor-acceptor (D-A) structured compound 1 based on the following specific design principles. First, the rod-like π-conjugated framework endows this molecule with abundant aggregation modes in the solid states, and the cyano stilbene group can rotate freely, thus resulting in interesting emission properties in solution. 26 Second, the aromatic-amine group being responsive to acid stimulus may induce significant changes in photophysical properties by disrupting the D-A nature. 27,28 Finally, the cyano and bulky CF 3 groups are expected to dramatically affect the molecular packing modes by hydrogen bonding interactions. 29 In the course of exploring the effects of environmental stimulus on the luminescent properties of this fluorophore, we found that the synthesized orange-red emissive solids exhibited interesting piezochromic fluorescence by the stimuli of grinding and heating, and the ground sample showed vapochromic emission upon exposure to organic vapor at ambient conditions. The solution of this compound and its protonated sample at room temperature (298 K) or under frozen conditions (77 K) gave totally different absorption and emission properties.Compound 1 was synthesized by a Knoevenagel reaction under gentle conditions in good yield (Scheme S1, Supporting Information). A column chromatography followed by vacuum sublimation gave rise to the pure product, which was fully characterized by 1 H NMR, mass spectra, element analyses, and finally X-ray crystal analysis. Upon being excited with UV light, the obtained orange powder and crystals exhibited bright orangered fluorescence with peaks centered at 587 (Φ f = 0.15) and 599 nm (Φ f = 0.14), respectively, and it was surpris...

Two sets of hydroxyphenyl-benzothiazole based compounds, which exhibited emission colors across the entire visible spectrum for both photoluminescence and electroluminescence, have been designed and synthesized.

No abstract

No abstract

A donor-acceptor-donor (D-A-D) molecule di(triphenylamine)-thiazolothiazole 1 has been employed in which the central Lewis-basic nitrogen atoms prompt it to be responsive to strong acids in both solution and solid states. As a result, the electron-accepting strength and intramolecular charge transfer (ICT) character can be controllably enhanced which make the emission band of 1 sequentially red-shift. The green luminescent solids (524 nm) can be smoothly transferred into yellow (576 nm), red (640 nm), and near infrared (739 nm) emissive states with a huge Dl em of 215 nm after being evaporated by HCl, TFA, and Lewis acid BBr 3 , respectively. Taking advantage of the smart sensitivity of 1 to acids, we prepared thermal-evaporated OLEDs based on the neutral and protonated species for the first time and achieved multicolor electroluminescence (EL) with very high brightness and moderate current efficiency. Thus, multicolor photoluminescence and thermally evaporated electroluminescence have been firstly realized based on a single organic chromophore, to the best of our knowledge.