Nanosized Prussian blue and its analogs for bioimaging and cancer theranostics

Prussian blue (PB) nanoparticles (NPs) and Prussian blue analogs (PBAs) can form metal-organic frameworks through the programmable coordination of ferrous ions with cyanide. PB and PBAs represent a burgeoning class of hybrid functional nano-systems with a wide-ranging application spectrum encompassing biomedicine, cancer diagnosis, and therapy. A comprehensive overview of recent advancements is crucial for gaining insights for future research. In this context, we reviewed the synthesis techniques and surface modification strategies employed to tailor the dimensions, morphology, and attributes of PB NPs. Subsequently, we explored advanced biomedical utilities of PB NPs, encompassing photoacoustic imaging, magnetic resonance imaging, ultrasound (US) imaging, and multimodal imaging. In particular, the application of PB NPs-mediated photothermal therapy, photodynamic therapy, and chemodynamic therapy to cancer treatment was reviewed. Based on the literature, we envision an evolving trajectory wherein the future of Prussian blue-driven biological applications converge into an integrated theranostic platform, seamlessly amalgamating bioimaging and cancer therapy. STATEMENT OF SIGNIFICANCE: Prussian blue, an FDA-approved coordinative pigment with a centuries-long legacy, has paved the way for Prussian blue nanoparticles (PB NPs), renowned for their remarkable biocompatibility and biosafety. These PB NPs have found their niche in biomedicine, playing crucial roles in both diagnostics and therapeutic applications. The comprehensive review goes beyond PB NP-based cancer therapy. Alongside in-depth coverage of PB NP synthesis and surface modifications, the review delves into their cutting-edge applications in the realm of biomedical imaging, encompassing techniques such as photoacoustic imaging, magnetic resonance imaging, ultrasound imaging, and multimodal imaging.

Roles of Hydrogen, Halogen Bonding and Aromatic Stacking in a Series of Isophthalamides

The synthesis and spectroscopic characterisation of six bis(5-X-pyridine-2-yl)isophthalamides (X = H, F, Br, Cl, I, NO2) are reported, together with five crystal structure analyses (for X = H, F to I). The isophthalamides span a range of conformations as syn/anti (H-DIP; I-DIP), anti/anti- (F-DIP; Br-DIP) and with both present in ratio 2:1 in Cl-DIP. The essentially isostructural F-DIP and Br-DIP molecules (using strong amide…amide interactions) aggregate into 2D molecular sheets that align with either F/H or Br atoms at the sheet surfaces (interfaces), respectively. Sheets are linked by weak C-H⋯F contacts in F-DIP and by Br⋯Br halogen bonding interactions as a ‘wall of bromines’ at the Br atom rich interfaces in Br-DIP. Cl-DIP is an unusual crystal structure incorporating both syn/anti and anti/anti molecular conformations in the asymmetric unit (Z’ = 3). The I-DIP•½(H2O) hemihydrate structure has a water molecule residing on a twofold axis between two I-DIPs and has hydrogen and N⋯I (Nc = 0.88) halogen bonding. The hydrate is central to an unusual synthon and involved in six hydrogen bonding interactions/contacts. Contact enrichment analysis on the Hirshfeld surface demonstrates that F-DIP, Cl-DIP and Br-DIP have especially over-represented halogen···halogen interactions. With the F-DIP, Cl-DIP and Br-DIP molecules having an elongated skeleton, the formation of layers of halogen atoms in planes perpendicular to the long unit cell axis occurs in the crystal packings. All six DIPs were analysed by ab initio calculations and conformational analysis; comparisons are made between their minimized structures and the five crystal structures. In addition, physicochemical properties are compared and assessed.

Probing the Electronic Properties and Interaction Landscapes in a Series of N-(Chlorophenyl)pyridinecarboxamides

A 3 × 3 isomer grid of nine N-(chlorophenyl)pyridinecarboxamides (NxxCl) is reported with physicochemical studies and single crystal structures (Nx = pyridinoyl moiety; xCl = aminochlorobenzene ring; x = para-/meta-/ortho-), as synthesized by the reaction of the substituted p-/m-/o-pyridinecarbonyl chlorides (Nx) with p-/m-/o-aminochlorobenzenes (xCl). Several of the nine NxxCl crystal structures display structural similarities with their halogenated NxxX and methylated NxxM relatives (x = p-/m-/o-substitutions; X = F, Br; M = methyl). Indeed, five of the nine NxxCl crystal structures are isomorphous with their NxxBr analogues as the NpmCl/Br, NpoCl/Br, NmoCl/NmoBr, NopCl/Br, and NooCl/Br pairs. In the NxxCl series, the favored hydrogen bonding mode is aggregation by N-H···N_pyridine interactions, though amide···amide intermolecular interactions are noted in NpoCl and NmoCl. For the NoxCl triad, intramolecular N-H···N_pyridine interactions influence molecular planarity, whereas NppCl·H₂O (as a monohydrate) exhibits O-H···O, N-H···O1W, and O1W-H···N interactions as the primary hydrogen bonding. Analysis of chlorine-containing compounds on the CSD is noted for comparisons. The interaction environments are probed using Hirshfeld surface analysis and contact enrichment studies. The melting temperatures (T _m) depend on both the lattice energy and molecular symmetry (Carnelley's rule), and the melting points can be well predicted from a linear regression of the two variables. The relationships of the T _m values with the total energy, the electrostatic component, and the strongest hydrogen bond components have been analyzed.

Monohalogenated carbamates where hydrogen bonding rules without halogen bonding: is there a link between poor carbamate crystal growth and Z′ > 1?

Monohalogenated carbamates (CxxX) aggregate by N–H⋯N interactions without halogen bonding and crystallise as poor quality crystalline fibres often with Z′ > 1.

Liquid phase synthesis of aromatic poly(azomethine)s, their physicochemical properties, and measurement of ex situ electrical conductivity of pelletized powdered samples

Aromatic bis-aldehydes have been used as building blocks in the synthesis of polyazomethines (a class of conjugated Schiff bases) and their physicochemical properties have been studied. Six dialdehydes have been synthesized, 3a-3f, via etherification reaction between aromatic diols (2a-2f) and 4-fluorobenzaldehyde (1) (see Scheme 1), and then polymerized with 1,4-phenylenediamine (4a) and 4,4'-oxydianiline (4b) (see Scheme 2). The chemical structures of the bis-aldehydes were elucidated by FTIR, ¹H NMR and ¹³C NMR spectroscopic studies, elemental analysis and single crystal whereas the polymers were studied by FTIR and NMR spectroscopy. Their physicochemical properties were examined by their inherent viscosity, organosolubility, differential scanning calorimetry, X-ray powder diffraction, thermogravimetric analysis, solvatochromism, and photoluminescence. We report the electrical conductivity of each polymer measured by the four probe method. The results indicate that the electrical conductivity of polymers lies in range 0.019-0.051 mScm^-1 which is reasonably higher than any reported value.

Two isostructural carbamates: the o-tolyl N-(pyridin-3-yl)carbamate and 2-bromo-phenyl N-(pyridin-3-yl)carbamate monohydrates

The title carbamate monohydrates, C13H12N2O2·H2O and C12H9BrN2O2·H2O, form isomorphous crystals that are isostructural in their primary hydrogen-bonding modes. In both carbamates, the primary hydrogen bonding and aggregation involves cyclic amide-water-pyridine moieties as (N-H⋯O-H⋯N)2 dimers about inversion centres [as R 4 (4)(14) rings], where the participation of strong hydrogen-bonding donors and acceptors is maximized. The remaining water-carbonyl O-H⋯O=C inter-action extends the aggregation into two-dimensional planar sheets that stack parallel to the (100) plane. The Br derivative does not participate in halogen bonding. A weak intra-molecular C-H⋯O hydrogen bond is observed in each compound.

Halogen bonding directed supramolecular assembly in bromo-substituted trezimides and tennimides

The imide-based trezimide and tennimide macrocycle crystal structures typically aggregate as 1-D chains through C–Br⋯OC/N/π(arene) halogen bonds (withN_c≤ 0.90) that dominate the solid-state aggregation process in the absence of classical strong hydrogen bond donors.

Structural systematics and conformational analyses of a 3 × 3 isomer grid of fluoro-N-(pyridyl)benzamides: physicochemical correlations, polymorphism and isomorphous relationships

An isomer grid of nine fluoro-N-(pyridyl)benzamides (Fxx) (x = para-/meta-/ortho-) has been examined to correlate structural relationships between the experimental crystal structure and ab initio calculations, based on the effect of fluorine (Fx) and pyridine N-atom (x) substitution patterns on molecular conformation. Eight isomers form N—H...N hydrogen bonds, and only one (Fom) aggregates via intermolecular N—H...O=C interactions exclusively. The Fpm and Fom isomers both crystallize as two polymorphs with Fpm_O (N—H...O=C chains, P-syn ) and Fpm_N (N—H...N chains, P-anti ) both in P21/n (Z′ = 1) differing by their meta-N atom locations (P-syn , P-anti ; Npyridine referenced to N—H), whereas the disordered Fom_O is mostly P-syn (Z′ = 6) compared with Fom_F (P-anti ) (Z′ = 1). In the Fxo triad twisted dimers form cyclic R 2 2(8) rings via N—H...N interactions. Computational modelling and conformational preferences of the isomer grid demonstrate that the solid-state conformations generally conform with the most stable calculated conformations except for the Fxm triad, while calculations of the Fox triad predict the intramolecular N—H...F interaction established by spectroscopic and crystallographic data. Comparisons of Fxx with related isomer grids reveal a high degree of similarity in solid-state aggregation and physicochemical properties, while correlation of the melting point behaviour indicates the significance of the substituent position on melting point behaviour rather than the nature of the substituent.

The Knoevenagel product of indolin-2-one and ferrocene-1,1'-dicarbaldehyde

Indolin-2-one (oxindole), (I), undergoes a Knoevenagel condensation with ferrocene-1,1'-dicarbaldehyde, (II), to afford the title complex 3,3'-[(E,E)-ferrocene-1,1'-diyldimethylidyne]diindolin-2-one dichloromethane disolvate, [Fe(C(28)H(20)N(2)O(2))]·2CH(2)Cl(2), (IV). The structure of (IV) contains two ferrocene complex molecules in the asymmetric unit and displays, as expected, intermolecular hydrogen bonding (N-H···O=C) between the indolin-2-one units. Intermolecular π-π stacking interactions are also observed.