Unlocking the Anticancer Potential of Frankincense Essential Oils (FEOs) Through Nanotechnology: A Review.

Cancer is a group of heterogeneous diseases that occur when cells in the body proliferate and divide uncontrollably. As the current treatment modalities have pros and cons, the discovery of new chemotherapeutic agents with the least side effects is one of the most investigated research areas. In this context, plant-based natural products are a rich source of drugs and have served humanity for ages. Frankincense essential oils (FEOs) are among the most promising plant-based oils in Gulf countries. In addition to their high cultural value, FEOs are also famous for their engaging biological activities, including anti-cancerous. However, the practical application of FEOs is often hindered/by their low water solubility, limited bioavailability, high volatility, and sensitivity toward heat, humidity, light, or oxygen. Thus, a significant demand for technological advancement would improve their ability to target particular cells and tissues. Nanotechnology emerged as an exciting approach in this context. Through suitable nano-formulation (functionalization or encapsulation into a nanostructure), issues arising due to solubility, targeting capability, and delivery can be controlled.

Heterometal Grafted Metalla-ynes and Poly(metalla-ynes): A Review on Structure-Property Relationships and Applications.

Metalla-ynes and poly(metalla-ynes) have emerged as unique molecular scaffolds with fascinating structural features and intriguing photo-luminescence (PL) properties. Their rigid-rod conducting backbone with tunable photo-physical properties has generated immense research interests for the design and development of application-oriented functional materials. Introducing a second d- or f-block metal fragment in the main-chain or side-chain of a metalla-yne and poly(metalla-yne) was found to further modulate the underlying features/properties. This review focuses on the photo-physical properties and opto-electronic (O-E) applications of heterometal grafted metalla-ynes and poly(metalla-ynes).

Synthesis and structural characterization of hexa-µ2-chlorido-µ4-oxido-tetra-kis-{[4-(phenyl-ethyn-yl)pyridine-κN]copper(II)} di-chloro-methane monosolvate.

In the crystal structure of the title compound, [Cu4Cl6O(C13H9N)4]·CH2Cl2, the core mol-ecular structure consists of a Cu4 tetra-hedron with a central inter-stitial O atom. Each edge of the Cu4 tetra-hedron is bridged by a chlorido ligand. Each copper(II) cation is coordinated to the central O atom, two chlorido ligands and one N atom of the 4-phenyl-ethynyl-pyridine ligand. In the crystal, the mol-ecules are linked by inter-molecular C-H⋯Cl inter-actions. Furthermore, C-H⋯π and π-π inter-actions also connect the mol-ecules, forming a three-dimensional network. Hirshfeld surface analysis indicates that the most important contributions for the packing arrangement are from H⋯H and C⋯H/H⋯C inter-actions.

Recent Advances in π-Conjugated N

Boron-containing π-conjugated materials are archetypical candidates for a variety of molecular scale applications. The incorporation of boron into the π-conjugated frameworks significantly modifies the nature of the parent π-conjugated systems. Several novel boron-bridged π-conjugated materials with intriguing structural, photo-physical and electrochemical properties have been reported over the last few years. In this paper, we review the properties and multi-dimensional applications of the boron-bridged fused-ring π-conjugated systems. We critically highlight the properties of π-conjugated N^C-chelate organoboron materials. This is followed by a discussion on the potential applications of the new materials in opto-electronics (O-E) and other areas. Finally, attempts will be made to predict the future direction/outlook for this class of materials.

Cyclometallated tridentate platinum(ii) arylacetylide complexes: old wine in new bottles.

Square planar platinum(ii) complexes have been known for 150 years and pincer complexes, supported by a tridentate chelating ligand such as terpyridyl, have been known for more than 70 years. The development of cyclometallated platinum(ii) pincer complexes, in which the tridentate ligand forms one or more platinum-carbon bonds, has been much more recent. Particularly, in terms of their solution and solid-state luminescence these cyclometallated complexes show substantial advantages over their terpyridyl analogues. This tutorial review introduces the reader to the area of platinum(ii) cyclometallated pincer chemistry and shows the advantage of having an alkynyl group in the fourth coordination site on the metal. The basic design principles for the preparation of highly luminescent platinum(ii) cyclometallated pincer complexes are outlined and the strategy to improve the luminescence further by chemical manipulation of the pincer ligand and of the auxiliary ligand in the fourth coordination site are illustrated with recent examples from the literature. Recent applications of these cyclometallated pincer complexes in the area of opto-electronics is described, with emphasis on their use in OLEDs, OFETs and as NLO materials as well as demonstrating their potential use as triplet photosensitizers and as metal ion sensors. The aim of this review is to show the recent advances in this rapidly developing research field and to highlight the future promise of these materials.

Rise of Conjugated Poly-ynes and Poly(Metalla-ynes): From Design Through Synthesis to Structure-Property Relationships and Applications.

Conjugated poly-ynes and poly(metalla-ynes) constitute an important class of new materials with potential application in various domains of science. The key factors responsible for the diverse usage of these materials is their intriguing and tunable chemical and photophysical properties. This review highlights fascinating advances made in the field of conjugated organic poly-ynes and poly(metalla-ynes) incorporating group 4-11 metals. This includes several important aspects of conjugated poly-ynes viz. synthetic protocols, bonding, electronic structure, nature of luminescence, structure-property relationships, diverse applications, and concluding remarks. Furthermore, we delineated the future directions and challenges in this particular area of research.

Impact of the Alkyne Substitution Pattern and Metalation on the Photoisomerization of Azobenzene-Based Platinum(II) Diynes and Polyynes.

Trimethylsilyl-protected dialkynes incorporating azobenzene linker groups, Me3SiC≡CRC≡CSiMe3 (R = azobenzene-3,3'-diyl, azobenzene-4,4'-diyl, 2,5-dioctylazobenzene-4,4'-diyl), and the corresponding terminal dialkynes, HC≡CRC≡CH, have been synthesized and characterized. The CuI-catalyzed dehydrohalogenation reaction between trans-[Ph(Et3P)2PtCl] and the deprotected dialkynes in a 2:1 ratio in iPr2NH/CH2Cl2 gives the platinum(II) diynes trans-[Ph(Et3P)2PtC≡CRC≡CPt(PEt3)2Ph], while the dehydrohalogenation polycondensation reaction between trans-[(nBu3P)2PtCl2] and the dialkynes in a 1:1 molar ratio under similar reaction conditions affords the platinum(II) polyynes, [-Pt(PnBu3)2-C≡CRC≡C-]n. The materials have been characterized spectroscopically, with the diynes also studied using single-crystal X-ray diffraction. The platinum(II) diynes and polyynes are all soluble in common organic solvents. Optical-absorption measurements show that the compounds incorporating the para-alkynylazobenzene spacers have a higher degree of electronic delocalisation than their meta-alkynylazobenzene counterparts. Reversible photoisomerization in solution was observed spectroscopically for the alkynyl-functionalized azobenzene ligands and, to a lesser extent, for the platinum(II) complexes. Complementary quantum-chemical modeling was also used to analyze the optical properties and isomerization energetics.

Experimental and Theoretical Investigation for the Level of Conjugation in Carbazole-Based Precursors and Their Mono-, Di-, and Polynuclear Pt(II) Complexes.

A series of trimethylsilyl-protected monoalkynes (Me3SiC≡C-R) and bis-alkynes (Me3 SiC≡C-R-C≡CSiMe3) incorporating carbazole spacer groups (R = carbazole-2-yl, carbazole-3-yl, carbazole-2,7-diyl, N-(2-ethylhexyl)carbazole-2,7-diyl, carbazole-3,6-diyl, N-(2-ethylhexyl)carbazole-3,6-diyl), together with the corresponding terminal monoalkynes (H-C≡C-R) and bis-alkynes (H-C≡C-R-C≡C-H), have been synthesized and characterized. The CuI-catalyzed dehydrohalogenation reaction between trans-[(Ph)(Et3P)2PtCl], trans-[(Et3P)2PtCl2], and trans-[(P(n)Bu3)2PtCl2] and the terminal alkynes in (i)Pr2NH/CH2Cl2 affords a series of Pt(II) mono- and diynes, while the dehydrohalogenation polycondensation reactions with trans-[(P(n)Bu3)2PtCl2] under similar reaction conditions yields four Pt(II) poly-ynes of the form trans-[(P(n)Bu3)2Pt-C≡C-R-C≡C-]n. The acetylide-functionalized carbazole ligands and the mono-, di-, and polynuclear Pt(II) σ-acetylide complexes have been characterized spectroscopically, with a subset analyzed using single-crystal X-ray diffraction. The Pt(II) mono-, di-, and poly-ynes incorporating the carbazole spacers are soluble in common organic solvents, and solution absorption spectra show a consistent red-shift between the 2- and 2,7- as well as 3- and 3,6-carbazole complexes. Computational modeling is used to explain the observed spectral shifts, which are related to the enhanced electronic delocalization in the latter systems. These results also indicate that the inclusion of carbazole-2,7-diyl units into rigid-rod organometallic polymers should enhance electronic transport along the chains.

New di-ferrocenyl-ethynylpyridinyl triphenylphosphine copper halide complexes and related di-ferricenyl electro-crystallized materials.

Three new neutral di-ferrocenyl-ethynylpyridinyl copper complexes, [L2(CuCl)2(PPh3)2] (), [L2(CuBr)2(PPh3)2] (), and [L2(CuI)2(PPh3)2] () were synthesized from the ferrocenyl-ethynylpyridine ligand (L) (), the appropriate copper halide CuX (with X = Cl(-), Br(-), I(-)) and triphenylphosphine. These neutral complexes were fully characterized by spectroscopic methods and by single crystal X-ray crystallography. Cyclic voltammetry in dichloroethane revealed chemically reversible ferrocenyl oxidation signals followed by characteristic "stripping reduction peaks" showing evidence for oxidation-product electro-crystallization. Scanning electron microscopy confirmed spontaneous formation of crystalline oxidation products with three distinct morphologies for X = Cl(-), Br(-), I(-). Energy dispersive X-ray elemental analysis data show Fe : P ratios of 1 : 2.0, 1 : 2.1 and 1 : 2.1 for electro-crystallization products of complexes , , and , respectively, indicating the presence of two [PF6](-) anions in the vicinity of the dioxidized complexes, and suggesting product formulae [](2+)[PF6](-)2, [](2+)[PF6](-)2 and [](2+)[PF6](-)2.

New multi-ferrocenyl- and multi-ferricenyl- materials via coordination-driven self-assembly and via charge-driven electro-crystallization.

Three new tetra-ferrocenylethynylpyridinyl copper complexes, L4(CuI)4 (3), L4(CuBr)2 (4), and L4(CuCl)2 (5) have been prepared from the reaction of ferrocenylethynylpyridine (L)(2) with copper halides CuX (with X = I(-), Br(-), Cl(-)).The ligand 2 and the complexes 3-5 have been fully characterized by spectroscopic methods. The structures of 2-4 have been confirmed by single-crystal X-ray crystallography. 2 forms a dimer in the crystalline-state through C-H··N hydrogen bonds. 4 and 5 are dimers and 3 a tetramer, in all cases linked through Cu-X··Cu bridging interactions. Cyclic voltammetry in dichloroethane showed chemically reversible multiferrocenyl oxidation signals with evidence for product electro-crystallization. The oxidation products were isolated by electrodeposition onto a Pt disc electrode and investigated by scanning electron microscopy which confirmed the spontaneous formation of crystalline oxidation products with distinctive morphologies. Energy dispersive X-ray elemental analysis shows the presence of hexafluorophosphate (counterion) with the P:Fe ratio of 1:1, 0.5:1, and 1:1 for the electrocrystallized products 3, 4, and 5, respectively, suggesting the formulas [3](4+)(PF6(-))4, [4](2+)(PF6(-))2, and [5](4+)(PF6(-))4 for the electro-crystallized products.

Long-range intramolecular electronic communication in bis(ferrocenylethynyl) complexes incorporating conjugated heterocyclic spacers: synthesis, crystallography, and electrochemistry.

A new series of bis(ferrocenylethynyl) complexes, 3-7, and a mono(ferrocenylethynyl) complex, 8, have been synthesized incorporating conjugated heterocyclic spacer groups, with the ethynyl group facilitating an effective long-range intramolecular interaction. The complexes were characterized by NMR, IR, and UV-vis spectroscopy as well as X-ray crystallography. The redox properties of these complexes were investigated using cyclic voltammetry and spectroelectrochemistry. Although there is a large separation of ∼14 Å between the two redox centers, ΔE(1/2) values in this series of complexes ranged from 50 to 110 mV. The appearance of intervalance charge-transfer bands in the UV-vis-near-IR region for the monocationic complexes further confirmed effective intramolecular electronic communication. Computational studies are presented that show the degree of delocalization across the Fc-C≡C-C≡C-Fc (Fc = C5H5FeC5H4) highest occupied molecular orbital.