Boron‐ and nitrogen‐doped polycyclic aromatic hydrocarbons (B‐PAHs) have established a strong foothold in the realm of organic electronics. However, their catalytic potential remains largely ...untapped. In this study, we synthesise and characterise two bench stable B,N‐doped PAH derivatives based on a 1,4‐azaborinine motif. Most importantly, the anthracene derived structure is an efficient catalyst in the reduction of various carbonyls and imines. These results underscore the potential of B,N‐PAHs in catalytic transformations, setting the stage for deeper exploration in this chemical space.
Bench stable 1,4‐azaborinine PAHs with an anthracene or ladder‐type pentacene scaffold have been prepared, characterised and proven to be efficient catalysts for hydroboration of carbonyls and imines.
Primary plasmodesmata (PD) arise at cytokinesis when the new cell plate forms. During this process, fine strands of endoplasmic reticulum (ER) are laid down between enlarging Golgi-derived vesicles ...to form nascent PD, each pore containing a desmotubule, a membranous rod derived from the cortical ER. Little is known about the forces that model the ER during cell plate formation. Here, we show that members of the reticulon (RTNLB) family of ER-tubulating proteins in Arabidopsis (Arabidopsis thaliana) may play a role in the formation of the desmotubule. RTNLB3 and RTNLB6, two RTNLBs present in the PD proteome, are recruited to the cell plate at late telophase, when primary PD are formed, and remain associated with primary PD in the mature cell wall. Both RTNLBs showed significant colocalization at PD with the viral movement protein ofTobacco mosaic virus, while superresolution imaging (three-dimensional structured illumination microscopy) of primary PD revealed the central desmotubule to be labeled by RTNLB6. Fluorescence recovery after photobleaching studies showed that these RTNLBs are mobile at the edge of the developing cell plate, where new wall materials are being delivered, but significantly less mobile at its center, where PD are forming. A truncated RTNLB3, unable to constrict the ER, was not recruited to the cell plate at cytokinesis. We discuss the potential roles of RTNLBs in desmotubule formation.
Fused-ring pyrazoles offer a versatile platform for derivitization to give finely tuned and functional ligands in coordination assemblies. Here, we explore the pyrazolo4,3-
b
pyridine (
HL1
) and ...pyrazolo3,4-
c
pyridine (
HL2
) backbones and their
N
-substituted derivatives, using their coordination chemistry with zinc(
ii
) in the solid state and in solution to examine the steric and electronic effects of varying their substitution pattern. The parent heterocycles
HL1
and
HL2
both generate robust and permanently porous isomeric MOFs on reaction with zinc and a dicarboxylate co-ligand. The subtle geometric change offered by the position of the backbone pyridyl nitrogen atom leads to substantial changes in the pore size and total pore volume, which is reflected in both their surface areas and CO
2
uptake performance. Both materials are also unusually resilient to atmospheric water vapour by virtue of the strong metal-azolate bonding. The isomeric chelating ligands
L3-L6
, generated by
N
-arylation of the parent heterocycles with a 2-pyridyl group, each coordinate to zinc to give either mononuclear or polymeric coordination compounds depending on the involvement of the backbone pyridine nitrogen atom. While crystal packing influences based on the steric preferences of the ligands are dominant in the crystalline phase, fluorescence spectroscopy is used to show that the
2H
isomers
L4
and
L6
show distinct coordination behaviour to the
1H
isomers
L3
and
L5
, forming competing ML and ML
2
species in soution. The first stability constant for
L6
with zinc(
ii
) is an order of magnitude larger than for the other three ligands, suggesting an improved binding strength based on the electron configuration in this isomer. These results show that careful control of remote substitution on fused pyrazole ligands can lead to substantial improvements in the stability of the resulting complexes, with consequences for the design of stable coordination assemblies containining labile metal ions.
Fused-ring pyrazoles offer a versatile platform for derivitization to give finely tuned and functional ligands in coordination assemblies.
Rice (Oryza sauva) takes up arsenite mainly through the silicic acid transport pathway. Understanding the uptake and sequestration of arsenic (As) into the rice plant is important for developing ...strategies to reduce As concentration in rice grain. In this study, the cellular and subcellular distributions of As and silicon (Si) in rice roots were investigated using high-pressure freezing, high-resolution secondary ion mass spectrometry, and transmission electron microscopy. Rice plants, both the Isil mutant lacking the Si/arsenite efflux transporter Lsi2 and its wild-type cultivar, with or without an iron plaque, were treated with arsenate or arsenite. The formation of iron plaque on the root surface resulted in strong accumulation of As and phosphorous on the epidermis. The mutant showed stronger As accumulation in the endodermal vacuoles, where the Lsi2 transporter is located in the plasma membranes, than the wild-type line. As also accumulated in the vacuoles of some xylem parenchyma cells and in some pericycle cells, particularly in the wild-type mature root zone. Vacuolar accumulation of As is associated with sulfur, suggesting that As may be stored as arsenite-phytochelatin complexes. Si was localized in the cell walls of the endodermal cells with little apparent effect of the Lsi2 mutation on its distribution. This study reveals the vacuolar sequestration of As in rice roots and contrasting patterns of As and Si subcellular localization, despite both being transported across the plasma membranes by the same transporters.
The synthesis of two π-extended pyrazole ligands is reported, with naphtho2,1-
d
-1
H
-pyrazole
HL1
prepared in a modified Jacobson indazole synthesis from 1-amino-2-methylnaphthalene, and subsequent ...arylation with 2-bromopyridine giving the chelating ligand
N
-(2-pyridyl)-naphtho1,2-
c
pyrazole
L2
as a single isomer, with both species crystallographically characterised. Each forms mononuclear complexes with Cu
2+
and Zn
2+
; in Cu(
HL1
)
4
(NO
3
)
2
1
and ZnCl
2
(
HL1
)
2
2
the propensity for outer-sphere hydrogen bonding from the pyrazole N-H group supplements the extended π backbone in influencing crystal packing interactions. The equivalent complexes of the chelating
L2
, Cu(
L2
)(NO
3
)
2
3
and ZnCl
2
(
L2
)
4
, both show distortion at the coordination sphere caused by the close approach of the hydrogen atom at the naphthyl 8-position, and crystal packing in both instances is dictated purely by the flat aromatic backbone of the ligand. Stability constants for complexes
3
and
4
are determined spectroscopically, and photophysical studies reveal fluorescence with vibrational progressions in both the solution and solid state for each ligand and the zinc complexes
2
and
4
.
The synthesis of two π-extended pyrazole ligands is reported, and their zinc(
ii
) and copper(
ii
) complexes are studied spectroscopically and crystallographically, revealing the influence of the fused naphthyl substituent.
Here we report the synthesis of two N -(2-picolyl) substituted bis-imide ligands, N,N′ -di(2-picolyl)-1,4,5,8-naphthalenetetracarboxylic diimide L1 and N , N′ -di(2-picolyl)-4,4′-oxybisphthalimide L2 ..., and describe their coordination chemistry in the crystalline state with late d -block metals, with the intention of probing the applicability of the recently reported N,O-chelating mode observed in N -(2-picolyl) substituted 1,8-naphthalimides. Four new crystalline coordination compounds have been prepared and structurally characterised; poly-Zn( L1 )Cl 2 ·3(C 3 H 6 O) 1 and poly-ZnCl 2 ( L1 )·MeCN 2 are structurally related one-dimensional coordination polymers whose extended structure contains well-defined solvent channels, the nature of which is coupled to the ability of the lattice solvent molecules to undergo n⋯π interactions with the 1,4,5,8-napthaletetracarboxylic diimide (NDI) core. H 2 L1 ZnCl 4 ·2H 2 O 3 is a hydrogen-bonded structure of tetrachlorozincate anions bound by the doubly protonated H 2 L1 cation, while repeating this reaction in the presence of copper( ii ) ions gave the ligand dihydrochloride salt ( H 2 L1 )2Cl 4 . Finally, reaction of L1 with AgSbF 6 gave the one-dimensional polymer poly-Ag L1 SbF 6 5 , in which weak but notable carbonyl coordination was observed in addition to stronger coordination from the pyridyl groups. Conversely, compound L2 failed to convincingly show any reaction or coordination with transition metals, and only the crystalline ligand itself could be isolated. Analysis of these results, as well as studies into the solution state coordination chemistry of these compounds, suggests an underlying barrier to coordination in these species compared to the 1,8-naphthalimides, but provides interesting avenues for crystal engineering.
The plant endoplasmic reticulum (ER) is crucial to the maintenance of cellular homeostasis. The ER consists of a dynamic and continuously remodelling network of tubules and cisternae. Several ...conserved membrane proteins have been implicated in formation and maintenance of the ER network in plants, such as RHD3 and the reticulon proteins. Despite the recent work in mammalian and yeast cells, the detailed molecular mechanisms of ER network organization in plants remain largely unknown. Recently, novel ER network-shaping proteins called Lunapark (LNP) have been identified in yeast and mammalian cells.
Here we identify two Arabidopsis LNP homologues and investigate their subcellular localization via confocal microscopy and potential function in shaping the ER network using protein–protein interaction assays and mutant analysis.
We show that AtLNP1 overexpression in tobacco leaf epidermal cells mainly labels cisternae in the ER network, whereas AtLNP2 labels the whole ER. Overexpression of LNP proteins results in an increased abundance of ER cisternae and lnp1 and lnp1lnp2 amiRNA lines display a reduction in cisternae and larger polygonal areas.
Thus, we hypothesize that AtLNP1 and AtLNP2 are involved in determining the network morphology of the plant ER, possibly by regulating the formation of ER cisternae.
The ability to use bio‐inspired building blocks in the assembly of novel supramolecular frameworks is at the forefront of an exciting research field. Herein, we present the first polyproline helix to ...self‐assemble into a reversibly porous, crystalline, supramolecular peptide framework (SPF). This framework is assembled from a short oligoproline, adopting the polyproline II conformation, driven by hydrogen‐bonding and dispersion interactions. Thermal activation, guest‐induced dynamic porosity and enantioselective guest inclusion have been demonstrated for this novel system. The principles of the self‐assembly associated with this SPF will be used as a blueprint allowing for the further development of helical peptide linkers in the rational design of SPFs and metal‐peptide frameworks.
The ability to use bio‐inspired building‐blocks in the assembly of novel supramolecular frameworks is at the forefront of an exciting research field. Herein, we present the first polyproline helix to self‐assemble into a reversibly porous, crystalline, supramolecular peptide framework (SPF). Thermal activation, guest‐induced dynamic porosity and enantioselective guest inclusion have been demonstrated for this novel system.
The synthesis of chiral α-amino acid derived (1,2,3-triazol-4-yl)-picolinamide (tzpa) ligands 4–6 designed by combining the coordination properties of two well-known ligand structures within a single ...unit is described. The self-assembly formation between these ligands and the lanthanide ion Tb(iii) was investigated in solution by probing the ground and the singlet excited state properties of the ligands as well as monitoring the evolution of the Tb(iii) emission at long wavelengths. The spectroscopic results showed that while under thermodynamic control the 1 : 3 (Tb : L) is produced, then analysis of the titration data using non-liner regression analysis demonstrated that the main species in solution is the 1 : 2 (Tb : L) after the addition of 0.5 equivalents of Tb(iii).
Flexible benzene-1,3,5-tricarboxamides (BTAs), organic species well-known for their tendencies to form functional soft-materials by virtue of their complementary hydrogen bonding, are explored as ...structurally reinforcing supramolecular building blocks in porous coordination polymers. We report the synthesis and characterisation of two related, carboxylate-terminated BTA derivatives, and the structure and functionality of their polymeric Cd(
ii
) complexes. The polycarboxylate ligand benzene-1,3,5-tricarboxamide tris(phenylacetic acid)
H
3
L1
was prepared, and the analogous trimethyl benzene-1,3,5-tricarboxamide tris acetate
Me
3
L2
was prepared and its single crystal structure elucidated. On reaction with cadmium nitrate in a DMF/H
2
O mixture, each BTA compound yielded coordination polymer species with columnar packing motifs comparable to the familiar BTA triple helix seen in purely organic systems. In the case of
Me
3
L2
, this transformation was achieved through a convenient
in situ
ester hydrolysis. Complex
1
is a 2-dimensional layered material containing tubular intralayer pores, in which amide-amide hydrogen bonding is a notable structural feature. In contrast, the structure of
2
contains no amide-amide hydrogen bonding, and instead a columnar arrangement of ligand species is linked by trinuclear Cd(
ii
) cluster nodes into a densely packed three-dimensional framework. The crystal structures revealed both materials exhibited significant solvent-accessible volume, and this was probed with thermal analysis and CO
2
and N
2
adsorption experiments; complex
2
showed negligible gas uptake, while compound
1
possesses an unusually high CO
2
capacity for a two-dimensional material with intralayer porosity and surprising structural resilience to guest exchange, evacuation and exposure to air.
Porous cadmium coordination polymers are prepared from structurally related benzenetricarboxamide ligands, and the functional influence of these scaffolds is examined.
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