Treatment of sodium 2-amino-5-mercapto-1,3,4-thiadiazolate (NaSSNH2) with monophosphines (triphenylphosphine and trimethylphosphine) and diphosphines [bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), and trans-1,2-bis(diphenylphosphino)ethene (dppee)] affords a series of gold(I) thiolates with the respective stabilizing phosphine ligands [Au(PR3)(SSNH2)] (R = Ph 1 and Me 2) and [PP(Au(SSNH2))2] (PP = dppm 3, dppe 4 and dppee 5). The crystal structures of the complexes have been determined by single-crystal X-ray diffraction studies, confirming hydrogen-bonded frameworks in the crystal lattices based on the functions of the SSNH2 ligands. The triphenylphosphine complex 1 (with crystal diethyl ether, 1·0.5Et2O) forms a dimer solely via bifurcated hydrogen bonds. In the presence of crystal methanol (1·MeOH) it gives rise to a one-dimensional ladder structure via intermolecular hydrogen-bonding interactions with molecules of crystal methanol as bridges. With a reduced steric effect of the auxiliary ligand, the trimethylphosphine analogue 2 forms a novel two-dimensional sheet structure via cooperative intermolecular aurophilic [Au(I)···Au(I) 3.0581(6) Å] and hydrogen-bonding interactions. The bis(diphenylphosphino)methane complex 3·2DMF features dinuclear units associated into a meandering chain structure via intramolecular aurophilic and intermolecular hydrogen bonding interactions. Further aggregation is terminated by hydrogen-bonding to crystal solvent molecules. 4·0.5MeOH forms a complicated network via cooperative intermolecular aurophilic [Au(I)···Au(I) 3.0675(7) Å] and hydrogen-bonding interactions. With DMF as a chain-terminating solvent molecule, the trans-1,2-bis(diphenylphosphino)ethylene complex 5·4DMF can only form isolated dinuclear units hydrogen bonded to these solvent molecules. Complexes 2 and 4 are rare examples of two-dimensional frameworks built on cooperative intermolecular aurophilic and hydrogen-bonding interactions in the solid state.

A 1D double-zigzag framework, {[Zn(paps)(2)(H(2)O)(2)](ClO(4))(2)}(n) (1; paps = N,N'-bis(pyridylcarbonyl)-4,4'-diaminodiphenyl thioether), was synthesized by the reaction of Zn(ClO(4))(2) with paps. However, a similar reaction, except that dry solvents were used, led to the formation of a novel 2D polyrotaxane framework, [Zn(paps)(2)(ClO(4))(2)](n) (2). This difference relies on the fact that water coordinates to the Zn(II) ion in 1, but ClO(4)(-) ion coordination is found in 2. Notably, the structures can be interconverted by heating and grinding in the presence of moisture, and such a structural transformation can also be proven experimentally by powder and single-crystal X-ray diffraction studies. The related N,N'-bis- (pyridylcarbonyl)-4,4'-diaminodiphenyl ether (papo) and N,N'-(methylenedi-para-phenylene)bispyridine-4-carboxamide (papc) ligands were reacted with Zn(II) ions as well. When a similar reaction was performed with dry solvents, except that papo was used instead of paps, the product mixture contained mononuclear [Zn(papo)(CH(3)OH)(4)](ClO(4))(2) (5) and the polyrotaxane [Zn(papo)(2)(ClO(4))(2)](n) (4). From the powder XRD data, grinding this mixture in the presence of moisture resulted in total conversion to the pure double-zigzag {[Zn(papo)(2)(H(2)O)(2)](ClO(4))(2)}(n) (3) immediately. Upon heating 3, the polyrotaxane framework of 4 was recovered. The double-zigzag {[Zn(papc)(2)(H(2)O)(2)](ClO(4))(2)}(n) (6) and polyrotaxane [Zn(papc)(2)(ClO(4))(2)](n) (7) were synthesized in a similar reaction. Although upon heating the double-zigzag 6 undergoes structural transformation to give the polyrotaxane 7, grinding solid 7 in the presence of moisture does not lead to the formation of 6. Significantly, the bright emissions for double-zigzag frameworks of 1 and 3 and weak ones for polyrotaxane frameworks of 2 and 4 also show interesting mechanochromic luminescence.

The treatment of [AuCl(SMe2 )] with an equimolar amount of NaO5 NCS2 (O5 NCS2 =(aza-[18]crown-6)dithiocarbamate) in CH3 CN gave [Au2 (O5 NCS2 )2 ]⋅2 CH3 CN (2⋅2 CH3 CN), and its crystal structure displays a dinuclear gold(I)-azacrown ether ring and an intermolecular gold(I)⋅⋅⋅gold(I) contact of 2.8355(3) Å in crystal lattices. It is noted that two other single crystals of 2⋅tert-butylbenzene⋅H2 O and 2⋅0.5 m-xylene can be successfully obtained from a single-crystal-to-single-crystal (SCSC) transformation process by immersing single crystals of 2⋅2 CH3 CN in the respective solvents, and both also show intermolecular gold(I)⋅⋅⋅gold(I) contacts of 2.9420(5) and 2.890(2)-2.902(2) Å, respectively. Significantly, the emissions of all three 2⋅solvates are well correlated with their respective intermolecular gold(I)⋅⋅⋅gold(I) contacts, where such contacts increase with 2⋅2 CH3 CN (2.8355(3) Å)<2⋅0.5 m-xylene (2.890(2)-2.902(2) Å)<2⋅tert-butylbenzene⋅H2 O (2.9420(5) Å), and their emission energies increase with 2⋅2 CH3 CN (602 nm)<2⋅0.5 m-xylene (583 nm)<2⋅tert-butylbenzene⋅H2 O (546 nm) as well. In this regard, we further examine the solvochromic luminescence for some other aromatics, and finally their emissions are within 546-602 nm. Obviously, the above results are mostly ascribed to the occurrence of intermolecular gold(I)⋅⋅⋅gold(I) contacts in 2⋅solvates, which are induced by the presence of various solvates in the solid state, as a key role to be responsible for their solvochromic luminescence.

There has been a growing interest in utilizing crystal engineering for the construction of a wide range of infinite solid-state architectures and metal-organic frameworks (MOFs). Such structures have been designed and structurally characterized by X-ray diffraction studies.[1] Moreover, their functionalities in chemical sieving, sensing, catalysis, and gas sorption have been also examined, and some have shown exciting and valuable potential.[2] However, a challenge encountered in designing the assembly of such materials is the unpredictability of the polymeric networks and dimensionalities, [1, 2] because they have been found to be structually dependent on the coordination geometry of the metal ions, metal/ligand ratios, flexibility of the ligand backbones, counterions, and solvents used in the reaction media. [3] Among the MOFs, there has been much attention directed to flexible and dynamic frameworks, [1g, 4] the structures and properties of which could be reversibly changed by external stimuli. In this regard, the design and synthesis of a host framework with dynamic behavior that can interact with certain guest molecules in a switchable and reversible manner is of interest as a new generation of functional materials. Although the effects of water as a guest molecule on the destabilization of some MOFs are known, the mechanism by which it brings about framework destabilization has been unclear. Up to now, only a handful of examples demonstrating framework destabilization in the transformation process have been studied experimentally by powder (PXRD) and single-crystal X-ray diffraction studies, [5] and hence more experimental results are necessary for elucidating the details of such interesting phenomena. Sauvage et al pioneered a new class of transition-metalcontaining rotaxanes, [6] which were suggested to be the basic elements for constructing nanoscale machines and motors in the future. Later, interpenetrating polyrotaxane networks in which macrocycles such as cyclic polyethers and cyclodextrins threaded onto 1D polymer chains were described. As a representative example, Robson et al in 1997 first reported two coordination polymers, [7] [Ag 2

A series of mononuclear and dinuclear platinum() thiolates with 2,2Ј-bipyridine (bpy) and 2,2Ј : 6Ј,2Љ-terpyridine (terpy) ligands having emissive LLCT (ligand-to-ligand charge-transfer) excited states were prepared and characterized by X-ray diffraction analyses. The [M 2 (dtbpy) 2 (NS) 2 ][ClO 4 ] 2 (M = Pt or Pd; dtbpy = 4,4Ј-di-tert-butyl-2,2Ј-bipyridine, NS Ϫ = pyridine-2-thiolate) complexes are isostructural to each other with intramolecular Pt ؒ ؒ ؒ Pt and Pd ؒ ؒ ؒ Pd distances being 2.917(2) and 2.891(4) Å, respectively. Assignment of LLCT absorption bands for the platinum() complexes was based on the shift in absorption energy with the substituents on the diimine and thiolate ligands. In the solid state or in solution at room temperature the platinum() complexes show photoluminescence with λ max ranging from 603 to 710 nm. The Pt II ؒ ؒ ؒ Pt II and/or ligand-ligand interactions are not primarily responsible for the emissions of the dinuclear platinum() thiolates which have intramolecular metal-metal separations greater than 2.9 Å.