Chen-Jie Fang

Luminescence Modulation of Ordered Upconversion Nanopatterns by a Photochromic Diarylethene: Rewritable Optical Storage with Nondestructive Readout

[*] Prof. C.-H. Yan, C. Zhang, H.-P. Zhou, L.-Y. Liao, Dr. W. Feng, Dr. W. Sun, Dr. Z.-X. Li, C.-H. Xu, Dr. C.-J. Fang, Prof. L.-D. Sun, Prof. Y.-W. Zhang Beijing National Laboratory for Molecular Sciences State Key Laboratory of Rare Earth Materials Chemistry and Applications PKU-HKU Joint Laboratory on Rare Earth Materials and Bioinorganic Chemistry Peking University Beijing 100871 (P. R. China) E-mail: yan@pku.edu.cn

Crystal structures and magnetic behaviour of three new azido-bridged dinuclear cobalt(II) and copper(II) complexes

Three dinuclear cobalt(II) and copper(II) complexes with double end-on (EO) azido bridges, [Co2(DMP)2(N3)4] (1), [Cu2(DMP)2(N3)4] (2) and [Cu2(PAP)2(N3)4] (3) (DMP = 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine; PAP = 1-phenyl-2-(2-pyridyl)-1-azapropylene) have been synthesized and characterized by single-crystal X-ray diffraction and magnetic analyses. The EPR spectra of powder samples for the two copper(II) complexes have also been examined at room temperature and 77 K, respectively. In the isomorphous complexes 1 and 2, the metal ions are penta-coordinated with distorted trigonal bipyramidal geometries, and the EO azido bridges assume an equatorial–axial disposition between metal ions. In contrast, the copper(II) ion in complex 3 adopts a distorted square pyramidal geometry, and the EO azido bridges assume a basal–apical disposition between metal ions. According to magnetic studies, the double end-on azido bridges mediate ferromagnetic coupling with J = 18.1 cm−1 in 1, antiferromagnetic coupling with J = −27.6 cm−1 in 2, and ferromagnetic coupling with J = 35.0 cm−1 in 3.

A Fluorescent‐Switch‐Based Computing Platform in Defending Information Risk

A molecular computing platform to defend against illegal information theft and invasion is obtained by the rational control of chemical reaction sequences in a newly prepared multiswitchable fluorophore 2-(4-aminophenylethylyl)-5-methoxy-2-(2-pyridyl)thiazole. Some of the fluorescent states with distinct recognition features are only activated through input-sequence-sensitive conversions. Chemically encoded user identity information can then be transmitted from a sequential logic unit to a combinational logic circuit, and hence, result in user-specific digital functionalities. The users password entry is authorized prior to each computing step to check not only the users identity, but also to reconfigure the molecular platform from the standby state to the corresponding operational state. Illegal accesses to the molecular computing platform are unable to activate the operation of the trusted users due to the incorrect activation processes, thereby ensuring the information is secured against information invasions.

New TTF derivatives: several molecular logic gates based on their switchable fluorescent emissions

The new redox-fluorescence dependent molecules MTs were synthesized with tetrathiafulvalene (TTF) and 5-methoxy-2-pyridylthiazoles coupled directly and rigidly. The fluorescent emission of MTs can be reversibly switched on/off depending on the oxidation states of the TTF unit, due to the peculiar property of TTF being oxidized reversibly and selectively. The dicationic MTs display a strong emission in the visible region and can be quenched by various chemical inputs. Based on this switchable fluorescent property of MTs, several logic gates such as AND, OR, NOT, NOR, INHIBIT, XNOR and NAND were realized by purposely selecting the initial states and chemical inputs.

Logic circuits constructed with an ion-sensitive fluorescent molecule 1,2-di[5-methoxy-2-(2-pyridyl)thiazoyl]ethyne

The fluorescence behaviours of a chemical-sensitive fluorescent molecule 1,2-di[5-methoxy-2-(2-pyridiyl)thiazoyl]ethyne (DMPTE) at different protonation and coordination states were studied. Upon addition of protons, metal ions and other chemicals, the fluorescent states can be switched reversibly. On the basis of the changes of fluorescence output signals from particular wavelengths in response to different combination sets of two particular external stimuli, the entire set of 2-bit Boolean binary logic functions were realized at the molecular level, including PASS 0, PASS 1, YES, NOT, OR, NOR, INHIBIT, IMPLICATION, AND, NAND, XOR, XNOR, and different logic functions were integrated reconfigurably within DMPTE. Besides, starting from the same initial state, a series of three-input logic gates and circuits were also constructed. Furthermore, the stepwise recognition process of DMPTE to different chemical input signals can also be utilized to distinguish different input sequences, thus a molecular keypad lock that authenticates three-digit password entries is indicated.

The crystal structures of four azido-bridged Zn(II) complexes based on open-chain diazine Schiff-base ligands

Four new Zn(II)-azido polymeric complexes with open-chain diazine Schiff-bases as auxiliary bridging ligands have been synthesized and crystallographically characterized. The differences in the constituents of the auxiliary ligands lead to three different types of polymeric structures. Complex 1, [Zn2(L1–H)(N3)3]n (L1 = 1,4-bis(2-pyridyl)-1-amino-4-methyl-2,3-diaza-1,3-butadiene), and complex 2, [Zn2(L2–H)(N3)3·H2O]n (L2 = 1,4-bis(2- pyridyl)-1,4-diamino-2,3-diaza-1,3-butadiene), show a similar one-dimensional (1D) coordination polymeric structure in which the building blocks of tetranuclear rings are interlinked by double end-on (EO) azido bridges, resulting in a “chain of rings” topology. Complex 3, {[Zn17(N3)24(L3–H)2(L3–2H)4(CH3OH)2]·(CH3OH)6·(H2O)3}n (L3 = butanedione monoxime picolinamide hydrazone) has a two-dimensional (2D) structure in which the Zn13 clusters are interlinked by Zn2 binuclear linkers to result in a (4,4) topology. The remaining complex 4, [Zn2(L4–H)(N3)3]n (L4 = 1-(2-pyridyl)-1-amino-4-methyl-4-thiazolyl-2,3-diaza-1,3-butadiene), has a three-dimensional (3D) network with a counterfeit CdSO4 topology, in which the 1D chains similar to those in complexes 1 and 2 are further interlinked by double EO azido bridges.

Azide-bridged Cd(II) 1D coordination polymer with Cd13 nano-crown-like cluster

A novel polymeric one-dimensional 2-acetylpyridine-supported cadmium(II)–azide shows tridecanuclear Cd13 crown-like clusters with defective supercubane cores, in which the azide ligands show μ-1,1- and μ-1,1,1-N3 bridging modes.

Orientational Organization of Organic Semiconductors within Periodic Nanoscale Silica Channels: Modification of Fluorophore Photophysics through Hierarchical Self‐Assembly

Smart nanomaterials: The orientational organization of small organic semiconductors (anthracene, in this case) within periodic nanoscale silica channels (see figure) is achieved through a novel hierarchical self-assembly approach. This elicits interesting optical effects and improved mechanical properties that could be of potential importance for functional materials.A novel hierarchical organic-inorganic self-assembly approach is proposed in driving the orientational organization of small organic semiconductors (anthracene, in this case). A cationic surfactant with the special organic semiconductor anthracene at the hydrophobic tail was synthesized and used as both the structure-directing agent and as functional nanobuilding blocks. The self-assembly procedure was rapid and allowed for the uniform and molecular-level controllable organization of the organic semiconductors within periodic nanoscale silica channels. A range of techniques were used to demonstrate that the photophysical and photochemical nature of anthracene is significantly altered in the inorganic host, consistent with orientational packing of the organic semiconductors and excimer formation within the channels, from which energy migration and significant emission occur. The nanocomposite has also been demonstrated to show an interesting selective sensor function with respect to small solvent molecules. We suggest that this method could be used to drive the assembly of a wide range of organic semiconductor guests, offering the development of a variety of useful, smart nanomaterials that are able to self-assemble in a controllable and robust fashion.

Four one-dimensional cadmium(II) polymers: one chairlike chain containing four azido bridging modes and three double end-on azido-bridged uniform chains

Four new azido-bridged cadmium(II) complexes have been synthesized and characterized by spectroscopy and crystallographic methods. Compounds [Cd3(L1)2(N3)6(H2O)(CH3OH)0.5]n (1), [Cd(L2)(N3)2]n (2), [Cd2(L3)(DMF)(N3)4]n (3) and [Cd(L4)(N3)2]n (4) (L1 = 2-acetylpyridine, L2 = 2-(pyrazol-1-ylmethyl)pyridine, L3 = 2-(3-methylpyrazol-1-ylmethyl)pyridine and L4 = 1-(2-pyridyl)-2-aza-1-amylene) show one-dimensional (1-D) polymeric structures in the lattice with the distorted octahedral coordination environment of the cadmium(II) ions in the four complexes. Compound 1 contains hexanuclear chairlike unit with defective dicubane-like core, which is further linked by azido bridges into a novel 1-D chain. It is interesting that four different azido bridging modes exist simultaneously in 1. Zigzag chains with double end-on (EO) azido bridged Cd(II) ions are formed in compound 2. Compounds 3 and 4 consist of uniform double EO azido bridged helical chains with screw-pitches of 18.91 and 26.04 A, respectively. It should be noted that the longer pitch in 4 is unusual in inorganic–organic hybrid complexes. Further comparison within the four chains shows that the rigidity of the chains increases with the steric effect of the co-ligands coordinated to the central Cd(II) ions.

Logic Information Communication in a Fluorescent Molecular Switch

Based on the chemical-sensitive fluorescence emission behaviors of the molecular switch 4-bromo-5-methoxy-2-(2-pyridyl)thiazole (2-BMPT), the communication of logic information between two functional units has been realized. With the rational control of the protonation and coordination reaction of 2-BMPT, an upstream switching unit (a 1:2 demultiplexer) and two downstream data-processing units are involved and interconnected in the communication. The two output states of the 1:2 demultiplexer serve as the initial input states of the two parallel downstream data-processing units, which execute the information communication between the two circuit layers. Furthermore, in the parallel data-processing layer, the logic gates of INHIBIT and YES accomplish their specific logic functions. Therefore, a molecular cascade circuit composed of an upstream switch and two downstream processing units has been constructed based on the chemical-modulated fluorescence properties of 2-BMPT.