The semiconductor Silicon (Si) remains a significant material in the electronic device and photovoltaic industries [1]. Especially, nanostructured forms of Si with a porous morphology (pSi) exhibit interesting properties which can be controlled via modulating pore structure and surface chemistry [1]. Recently, synthesis of a unique one-dimensional form of Si, namely nanotubes, with tunable structure (shell thickness, length, inner diameter and porous morphology) has been demonstrated, thereby suggesting newly emerging applications [2]. For instance, recent works have indicated Si nanotubes (SiNTs) can efficiently serve as a reaction vessel for formation of organometal perovskite nanostructures and a template for superparamagnetic iron oxide (Fe3O4) loading [3], [4]. In an observation of dissolution of SiNTs with a porous morphology (pSiNTs), the material readily resorbed in buffered media at physiological conditions in a similar manner to bioactive nanostructured porous silicon, thereby implying potential therapeutic applications of this material [2].
In chemotherapy, platinum-based cancer drugs, such as cisplatin and carboplatin, are widely used as effective drugs against various types of cancer [5]. Interestingly, while elemental platinum nanoparticles (Pt NPs) have been well investigated in diverse catalytic processes, in recent years, Pt NPs have also been discovered as a potent anti-cancer agent in nanomedicine, implying the use of the nanodrug to counteract chemoresistance in some cancer cell lines [6], [7]. Recent reports have also indicated that enhanced cytotoxicity against selected cancer cell lines is ascribed to ultra-small Pt NPs, especially those with size less than 3 nm [7]. In this report, pSiNTs were investigated as a template for the formation of Pt NPs, and in vitro cytotoxicity of the composites was evaluated against HeLa cancer cells.
Regarding fabrication, pSiNTs with short lengths (~500 nm) and thin walls (~10 nm) were synthesized via a ZnO nanowire sacrificial template method. Based on a combination of characterization techniques [High resolution transmission electron microscopy (HR-TEM) and energy dispersive X-ray analysis (TEM-EDX)], it is suggested that pSiNTs surface functionalized with 3-aminopropyltriethoxysilane can facilitate formation of Pt nanocrystals (Pt NCs) with size ranging from 1-3 nm utilizing a K2PtCl4 precursor. By varying reaction conditions (concentration of Pt salt and incubation time), the amount of Pt NCs deposited on SiNTs can be sensitively tuned from 20 to 55 wt%. In terms of cytotoxicity evaluation of the composites against HeLa cells, cellular viability was assessed using CellTiter-Glo assays, which quantified the amount of ATP in metabolically active cells. Our findings suggest that Pt NCs-SiNTs composites were toxic to HeLa cells, and less than 50% cells were still viable after 3 days of treatment with the composites at doses of 35 μg/ml and 50 μg/ml. Results from caspase 3/7 assays also showed that caspase 3/7 level in cells treated with Pt NCs-SiNTs approximately ranged from 1.5 to 2-fold increase compared to cells without treatment, thereby suggesting apoptosis as the likely mechanism. In vitro cellular uptake studies analyzed by confocal microscopy also confirmed accumulation of the composites within the cytoplasm of the cells after the treatment, consistent with a “Trojan horse” mechanism in which high concentrations of Pt NCs are internalized within cells assisted by pSiNTs and subsequently released via dissolution of the nanotube matrix.
The studies presented herein describe a novel strategy to form and immobilize highly compact clusters of Pt NCs by using pSiNTs as a template. In terms of bio-relevant applications, in vitro studies provide new insights into the anti-cancer properties of the newly discovered composites in inducing apoptosis in HeLa cells, thereby providing significant potential uses of Pt NCs-SiNTs in cancer treatment. Further investigations into gene expression profile(s) may be necessary in order to clarify the impact of the composites on cell survival in terms of molecular mechanisms.
References
1. H. Santos, Porous Silicon for Biomedical Applications, Ed. Cambridge: Woodhead Publishing, (2014).
2. X. Huang, R. Gonzalez-Rodriguez, R. Rich, Z. Gryczynski and J. L. Coffer, Chem. Commun., 49, 5760 (2013).
3. R. Gonzalez-Rodriguez, N. Arad-Vosk, N. Rozenfeld, A. Sa'ar and J. L. Coffer, Small, 12(33), (2016).
4. P. Granitzer, K. Rumpf, R. Gonzalez, J. Coffer, M. Reissner, Nanoscale Res. Lett., 9, 413 (2014).
5. T. C. Johnstone, K. Suntharalingam and S. J. Lippard, Chem. Rev., 116 (5), 3436–3486, (2016).
6. X. Li, G. Li, W. Zang, L. Wang and X. Zhang, Catal. Sci. Technol., 4, 3290-3297 (2014).
7. H. Xia, F. Li, X. Hu, W. Park, S. Wang, Y. Jang, Y. Du, S. Baik, S. Cho, T. Kang, D. Kim, D. Ling, K. M. Hui and T. Hyeon, ACS Cent. Sci., 2, 802−811 (2016).

The chemical hardness of a solvent can play a decisive role in solubility and reactivity in solution. Several empirical scales of solvent softness have been proposed. We explore whether computed properties of solvent molecules can reproduce these empirical scales. Our "orbital overlap distance" quantifying the size of orbitals at a molecule's surface effectively reproduces the Marcus μ-scale of solvent softness. The orbital overlap distance predicts that the surfaces of chemically hard solvent molecules is dominated by compact orbitals possessing a small orbital overlap distance. In contrast, the surface of chemically soft solvent molecules has a larger contribution from diffuse orbitals and a larger orbital overlap distance. Other "conceptual density functional theory" descriptors, including the global hardness and electronegativity, can also reproduce empirical solvent scales. We further introduce a "solvent versatility" RMSD Dsurf scale quantifying variations in the surface orbital overlap distance. "Good" solvents such as DMSO, which combine chemically "hard" and "soft" sites within a single molecule, possess a large RMSD Dsurf. We conclude by applying this approach to predict the Marcus μ-parameters for widely-used ionic liquids and ionic liquid - cosolvent systems.

The use of macrocyclic pyridinophane has been growing in the fields of bioinorganic modeling, catalysis and imaging. However, the functionalization of the pyridine has not been fully explored. Therefore, the Green Research Group we produce a series of 12-membered tetra-aza N-heterocyclic amines, derived from pyclen with different functional groups substituted at the para position. Using Hammett plot analysis, X-ray diffraction, electrochemistry and C-C coupling catalytic results, we aim to understand the impact of these functional groups on the donating) of the ligand. From the Hammett plot results we predict how other functional groups will affect the electronics and reveal whether the resonance or inductive effects will mitigate the coordination environment.
The use of macrocyclic pyridinophane has been growing in the fields of bioinorganic complexes modeling, catalysis, and imaging. However, the functionalization of the pyridine has not been fully explored. Therefore, the Green Research Group produced a series of 12-membered tetra-aza macrocycles derived from pyclen with different functional groups substituted at the para position. Using Hammett plot analysis, X-ray diffraction, electrochemistry, and C-C coupling catalytic results, we aim to understand the impact of these functional groups on the donor ability of each ligand. From the Hammett plot results we hope to predict how other functional groups will affect the electronics and reveal whether the resonance or inductive effects will mitigate the coordination environment and reactivity of each complex.

Phenanthridone-type alkaloids isolated from certain plants of the Amaryllidaceae family are of interest due to their pharmaceutically active nature. The compounds are commonly used in research concerning cancer, Alzheimer’s disease and other human illnesses. One of the main hindrances to such research is the limited availability of many of these compounds. The Minter group is interested in the development of procedures for synthesizing such alkaloids in a cost-effective and time efficient manner, while at the same time maintaining fair to excellent yields.
Techniques toward the synthesis of natural products of the Phenanthridone type are presented herein. Manipulations were tested and optimized on a model system in order to save both time and funds while developing a synthetic pathway to be utilized in the formation of more complex compounds. Setbacks such as controlling the stereochemistry of a tetra-substituted double bond reduction have been encountered. However, adjustments are being made to avoid such difficulties in the future. Ideally, the proposed scheme will ultimately allow for the synthesis of multiple phenanthridone analogs.

In chemistry, cyclic compounds of twelve or more atoms are considered macrocycles. Many bioactive, natural products containing macrocycles have been isolated and synthesized. Still, construction of macrocycles is usually considered a challenging step in their synthesis. Here, a route to different-sized macrocycles is described. These macrocycles arise from spontaneous cyclization of two identical subunits comprising a central triazine displaying both a masked aldehyde and hydrazine group. The aldehyde portion is presented on a linker that can comprise varying number of carbons. By varying this linker, macrocycles of 22, 24, and 26 atoms have been prepared. Future study focuses on probing macrocycle size with increasingly larger linkers.