1wileyonlinelibrary.com creation of electronic based communication methods that substitute for paper has not been as rapid as was expected, which is evidenced by threefold increase in the global consumption of paper over the past few decades. [1,2] According to findings made in recent surveys, most documents containing information recorded on paper are disposed after a one-time use. This trend is creating serious and growing environmental problems associated with deforestation, solid waste, and chemical pollution in air, water, and on land. [3,4] As a result, much attention has been given to the development of rewritable paper that can be used multiple times. If successful, the new technology would help bring about a balance between the socioeconomic advancement of society and environmental protection. In this context, several types of rewritable papers and erasable inks have been described recently. One elegant approach to this problem utilizes a rewritable composite paper, containing a photocatalyzed, color switchable redox dye. In this system, ink-free replication of a text/pattern created by using a preprinted photomask is possible. [5] In another remarkable effort, a hydrochromic dye embedded paper was designed for water-jet printing where water serves as the trigger for color switching. [6] By taking advantage of their tunable refractive index property, photonic crystals have been utilized to fabricate rewritable paper. In this system, a well-ordered photonic coating is embedded on substrate for pattern-on-demand printing using water, [7] hygroscopic salts, [8] and silicon fluid [9] as inks. Furthermore, a wide range of photoresponsive color switchable functionalized azobenzenes, [10,11] flugides, [12,13] bisthienylethenes, [14] spironapthooxazine, [15] and spiropyrans [16] have been explored in potential rewritable paper applications. In similar approaches, phenomenon involving reversible halochromism of oxazine derivatives [17] and thermochromism of leuco dyes [18,19] has been employed to develop rewritable paper systems.In the investigation described below, we devised and tested a new strategy for the design of light-responsive ink for rewritable paper, which is based on the photochromic switching properties of diarylethenes (DEs). DEs are known to undergo light-stimulated (UV-vis) reversible photochemical cyclization and cycloreversion reactions, which are accompanied by color switching from colored closed to colorless open ring forms. Full Color Light Responsive Diarylethene Inks for Reusable PaperWoomin Jeong, Mohammed Iqbal Khazi, Dong-Hoon Park, Young-Sik Jung, and Jong-Man Kim* "Digitalization" represents one approach to shift society's dependence on paper-based communication. However, thus far, this tactic has not had a significant impact on global paper consumption, which has risen over the past few decades. The escalating demand of paper making and consumption has resulted in an intensified negative effect on the environment. Because of this, the development of rewritable paper or erasable ink a...

Tubular materials formed by self-assembly of small organic molecules find great utility in chemical and material science. Conventional tubular structures often lack stability because noncovalent molecular interactions are responsible for their conformational integrities. Herein we report the development of covalently linked chromogenic organic nanotubes which are prepared by using topochemical polymerization of self-assembled macrocyclic diacetylenes (MCDAs). Crystal structures of five MCDAs having different diameters were elucidated, and four of these substances were transformed to tubular polydiacetylenes (PDA) by UV-induced polymerization. Surprisingly, MCDA-1 was found to self-assemble in stacks with a tilt angle of 62.1°, which significantly deviates from the optimal value for polymerization of 45°. This observation suggests that geometric parameters derived using linear diacetylene (DA) models might not be strictly applicable to polymerization of MCDA systems. Blue-phase PDAs obtained by polymerization of MCDA-1 and MCDA-3 have different thermochromic and solvatochromic properties, which enable them to be utilized for colorimetric differentiation of aromatic solvents including isomeric xylenes. The observations made and information obtained in this study should enhance the understanding and design of stimulus-responsive rigid organic nanotubes.

a b s t r a c tPicornaviruses (PV) and coronaviruses (CoV) are positive-stranded RNA viruses which infect millions of people worldwide each year, resulting in a wide range of clinical outcomes. As reported in this study, using high throughput screening against 6800 small molecules, we have identified several novel inhibitors of SARS-CoV 3CL pro with IC 50 of low lM. Interestingly, one of them equally inhibited both 3C pro and 3CL pro from PV and CoV, respectively. Using computer modeling, the structural features of these compounds as individual and common protease inhibitors were elucidated to enhance our knowledge for developing anti-viral agents against PV and CoV.

A new series of fully aliphatic polyimide (API) based on a novel aliphatic dianhydride monomer-2,2 0 -(1,4-piperazinediyl)-disuccinic anhydride (PDA), in which two units of succinic anhydride have been connected by an aliphatic heterocyclic piperazine spacer that possesses aminomethylene (-NCH 2 ) moiety in the aliphatic/alicylic backbone capable of inducing charge transfer (CT) interactions in the polyimide network, was successfully synthesized. The APIs were soluble in common polar organic solvents. The polyimide films of PDA with alicyclic diamines were almost colorless. T 10 (temperature of 10% weight loss) of APIs were ranged from 299-418 C and T g of API3-API6 were in the temperature range of 170 to 237 C. The light-colored polyimide films of API3-API6 possessed good mechanical properties with tensile strength of 54-72 Mpa, tensile modulus of 1.6-2.3 Gpa and elongation at break of 4-9%. The polyimide films of API3-API6 were highly flexible and freestanding which is quite rare in fully APIs. The dielectric constant of one of the synthesized API (API4) was as low as 2.14.

No abstract