Dual-Stimulus-Driven Dynamically Controllable [3]Rotaxane with Tunable Organic Room-Temperature Phosphorescence.

A dual-stimulus-driven stiff-stilbene-based dynamic [3]rotaxane has been facilely developed using the threading-stoppering strategy and exhibits reversible shuttling motions and bidirectional rotations upon encountering acid-base and distinct light stimulations, respectively. Herein, the two dibenzo-24-crown-8 macrocycles can undergo reversible switching motion between two different stations along the axle suffered from acid-base stimulation, and simultaneously, the two rotaxanes can also perform cis-trans rotations upon irradiation with distinct light. In other words, the constructed rotaxanes can conduct two modes of regular motions without interference. Interestingly, reciprocating switching motion of the rings along the axle enabled the rotaxanes to exhibit controllable and reversible photoisomerization speed, conversion yield, and quantum yield. Crucially, these rotaxanes also manifest adjustable solid-state organic room-temperature phosphorescence (RTP) and photoluminescence stimulated by dual factors (acid-base and diverse light), which are further applied in information encryption and anticounterfeiting. The presented study provides an instructive way for precisely boosting photoisomerization performances and the fabrication of dual-stimuli-induced molecular machines with functions of two-mode mechanical motions and controllable pure organic RTP switches.

Recent advances in transition-metal-catalyzed Büchner reaction of alkynes.

Medium-sized ring-containing organic molecules, especially seven-membered rings, are significant structural motifs. However, such frameworks are considered difficult structures to access owing to entropic effects and transannular interactions. Compared to the construction of five and six-membered rings, the synthesis of seven-membered rings can be more challenging through traditional cyclization pathways. Büchner reactions are particularly attractive and efficient synthetic strategies to construct functionalized seven-membered ring products from the benzenoid double bond with carbene. In recent years, the field of transition-metal-catalyzed Büchner ring expansion reactions of alkynes has experienced a speedy development and a diverse array of efficient synthetic procedures have been disclosed under mild experimental conditions, as the synthesis of synthetically challenging seven-membered rings is easily achieved. In this review, we will focus on the recent progress in the transition-metal-catalyzed Büchner reaction of alkynes and the mechanistic rationale is depicted where possible, with the reactions being sorted according to the type of catalyst.

Plant Metabolites Drive Different Responses in Caterpillars of Two Closely Related Helicoverpa Species.

The host acceptances of insects can be determined largely by detecting plant metabolites using insect taste. In the present study, we investigated the gustatory sensitivity and feeding behaviors of two closely related caterpillars, the generalist Helicoverpa armigera (Hübner) and the specialist H. assulta (Guenée), to different plant metabolites by using the single sensillum recording technique and the dual-choice assay, aiming to explore the contribution of plant metabolites to the difference of diet breadth between the two species. The results depicted that the feeding patterns of caterpillars for both plant primary and secondary metabolites were significantly different between the two Helicoverpa species. Fructose, glucose, and proline stimulated feedings of the specialist H. assulta, while glucose and proline had no significant effect on the generalist H. armigera. Gossypol and tomatine, the secondary metabolites of host plants of the generalist H. armigera, elicited appetitive feedings of this insect species but drove aversive feedings of H. assulta. Nicotine and capsaicin elicited appetitive feedings of H. assulta, but drove aversive feedings of H. armigera. For the response of gustatory receptor neurons (GRNs) in the maxillary styloconic sensilla of caterpillars, each of the investigated primary metabolites induced similar responding patterns between the two Helicoverpa species. However, four secondary metabolites elicited different responding patterns of GRNs in the two species, which is consistent with the difference of feeding preferences to these compounds. In summary, our results of caterpillars' performance to the plant metabolites could reflect the difference of diet breadth between the two Helicoverpa species. To our knowledge, this is the first report showing that plant secondary metabolites could drive appetitive feedings in a generalist insect species, which gives new insights of underscoring the adaptation mechanism of herbivores to host plants.

Bis[N'-(3-cyano-benzyl-idene)isonicotino-hydrazide]silver(I) trifluoro-acetate.

In the title compound, [Ag(C(14)H(10)N(4)O)(2)]CF(3)CO(2), the Ag(I) ion is coordinated by two N atoms of the pyridine rings of two N'-(3-cyano-benzyl-idene)isonicotinohydrazide ligands in a nearly linear geometry. In the crystal structure, a combination of close contacts formed via Ag⋯N inter-actions [Ag⋯N = 3.098 (2) and 3.261 (2) Å] from symmetry-related mol-ecules and inter-molecular N-H⋯O hydrogen bonds between CF(3)CO(2) (-) anions and the hydrazone groups of two ligands give rise to chains. Furthermore, there are Ag⋯O inter-actions with a separation of 2.765 (2) Šbetween chains. The F atoms of the CF(3)CO(2) (-) anion are disordered over two sites with refined occupancies of 0.593 (5) and 0.407 (5).

Dichlorido(2,9-diprop-oxy-1,10-phenanthroline-κN,N')cadmium(II).

In the title complex, [CdCl(2)(C(18)H(20)N(2)O(2))], the Cd(II) ion is coordinated by two N atoms from a bis-chelating 2,9-diprop-oxy-1,10-phenanthroline ligand and two Cl atoms in a distorted tetra-hedral environment. The two Cd-Cl bond distances are significantly different from each other and the N-Cd-N bond angle is acute. In the crystal structure, there are π-π stacking inter-actions between symmetry-related phenanthroline ring systems, with a centroid-centroid distance of 3.585 (3) Å.

Dichlorido(2,9-dieth-oxy-1,10-phenanthroline-κN,N')zinc(II).

All non-H atoms except for the Cl atoms lie on a mirror plane in the title complex, [ZnCl(2)(C(16)H(16)N(2)O(2))]. The Zn(II) ion is coordinated by two N atoms from a bis-chelating 2,9-dieth-oxy-1,10-phenanthroline ligand and two symmetry-related Cl atoms in a distorted tetra-hedral environment. The two Zn-N bond lengths are significantly different from each other and the N-Zn-N angle is acute. In the crystal structure, there are weak but significant π-π stacking inter-actions between phenanthroline rings, with a centroid-centroid distance of 3.764 (1) Å.

catena-Poly[[[diaqua-bis(2-methyl-6-oxo-1,6-dihydro-3,4'-bipyridine-5-carbo-nitrile)copper(II)]-µ-sulfato] tetra-hydrate].

In the title polymer, {[Cu(SO(4))(C(12)H(9)N(3)O)(2)(H(2)O)(2)]·4H(2)O}(n), both the metal center and the sulfate anion are located on a twofold axis. The Cu(II) ion is coordinated by two pyridyl N atoms from two symmetry-related organic ligands, two O atoms from two symmetry-related water mol-ecules, and two O atoms from two symmetry-related sulfate anions, resulting in a distorted octa-hedral geometry. The sulfate anions act as µ(2)-bridges and connect metal ions, forming a one-dimensional chain along the b axis. The three-dimensional crystal structure is established through inter-molecular N-H⋯O and O-H⋯O hydrogen bonds involving the organic ligands, sulfate anions, coordinated and uncoordinated water mol-ecules, and through π-π inter-acting 2-pyridone rings, with centroid-centroid separations of ca 3.96 Šand tilt angles of ca 2.62°.

catena-Poly[[[N'-(4-cyano-benzyl-idene)nicotinohydrazide)silver(I)]-µ-N'-(4-cyano-benzyl-idene)nicotinohydrazide] hexa-fluorido-phosphate].

In the title polymer, {[Ag(C(14)H(10)N(4)O)(2)]PF(6)}(n), each Ag(I) ion is coordinated by two N atoms from two pyridyl rings of independent N'-(4-cyano-benzyl-idene)nicotinohydrazide ligands, and one N atom from one carbonitrile group of a symmetry-related ligand in a distorted T-shaped geometry. The ligands exhibit two modes of coordination. One acts as a bridge connecting Ag atoms to form one-dimensional chains along [01]. The other acts as a terminal monodentate ligand, coordinating to Ag through its pyridyl N atom. Two neighbouring anti-parallel chains in the crystal are connected through N-H⋯O hydrogen bonds. Other adjacent chains are packed via Ag⋯O inter-actions, with Ag⋯O separations of 2.876 (2) Å. In addition, PF(6) (-) counter-anions inter-act with the hydrazone groups through N-H⋯F hydrogen bonds. The PF(6) (-) anion is disordered over two sites, with occupancies of 0.773 (8) and 0.227 (8).