R ecently, the National Science Foundation projected that the current 10-billion dollar nanotechnology sector will employ 2 million workers, including as many as 1 million workers in the United States. 1 It is expected that over 80% of the jobs created in this sector will require trained individuals in nanoscience. However, little training at the undergraduate level has been initiated to provide highly specialized scientists to this rapidly developing field. The proposed laboratory experiment, which was implemented for both undergraduate and graduate student laboratories in physical chemistry and nanotechnology, addresses the future projected demand.In 1998, G. C. Weaver and K. Norrod proposed an undergraduate laboratory to introduce the surface-enhanced Raman scattering (SERS) effect and to extend the scope of the Raman theory normally covered in physical chemistry courses. 2 A Raman-active molecule, pyridine, was adsorbed on colloidal silver nanoparticles (AgNPs) to demonstrate the large increase in Raman signal. Although successful, the SERS experiment did not estimate the analytical enhancement factor (AEF) and surface enhancement factor (SEF), the most important values for characterizing the SERS effect. 3,4 The Raman signal enhancement of 100À300 times was simply determined by calculating the ratio of integrated areas for specific vibrational modes of pyridine adsorbed on AgNPs and in solution. However, the pyridine concentrations (1.0 Â 10 À1 M for normal Raman and 6.25 Â 10 À3 M for SERS measurements) were extremely large when compared with the trace amounts of analyte that are now detected via SERS. In the following years, theoretical and experimental studies have demonstrated that single-molecule SERS-based detection and identification can be achieved under favorable circumstances. 5,6 Because of the enormous enhancement, SERS found numerous cutting-edge applications in medical, biological, chemical, military defense, homeland security, pharmacological, and environmental settings. 7À9 Most SERSbased detection and identification applications require an accurate determination of the magnitude of the signal enhancement.In this experiment, Raman and fluorescence spectrophotometers were employed to estimate the analytical and surface enhancement factors for rhodamine 6G adsorbed on a Creighton colloid. 10 Among the many kinds of SERS-active substrates, silver colloids are known to lead to huge enhancement factors and to enable single-molecule SERS experiments. 5À7,11 The Creighton method has been widely used for its simplicity, relative low cost, accessibility, and time efficiency. These parameters were critical in designing a feasible experiment for a laboratory. Not surprisingly, in 2007, Solomon et al. implemented the Creighton procedure for the synthesis of colloidal AgNPs as a new laboratory experiment for a general chemistry class. 12

Physisorption of molecular hydrogen based on neutral and negatively charged aromatic molecular systems has been evaluated using ab initio calculations to estimate the binding energy, DeltaH, and DeltaG at 298 ( approximately 77 bar) and 77 K (45 bar) in order to compare calculated results with experimental measurements of hydrogen adsorption. The molecular systems used in this study were corannulene (C(20)H(10)), dicyclopenta[def,jkl]triphenylene (C(20)H(10)), 5,8-dioxo-5,8-dihydroindeno[2,1-c]fluorene (C(20)H(10)O(2)), 6-hexyl-5,8-dioxo-5,8-dihydroindeno[2,1-c]fluorene (C(26)H(22)O(2)), coronene (C(24)H(12)), dilithium phthalocyanine (Li(2)Pc, C(32)H(16)Li(2)N(8)), tetrabutylammonium lithium phthalocyanine (TBA-LiPc, C(48)H(52)LiN(9)), and tetramethylammonium lithium phthalocyanine (TMA-LiPc, C(36)H(28)LiN(9)). It was found (a) that the calculated term that corrects 0 K electronic energies to give Gibbs energies (thermal correction to Gibbs energy, TCGE) serves as a good approximation of the adsorbent binding energy required in order for a physisorption process to be thermodynamically allowed and (b) that the binding energy for neutral aromatic molecules varies as a function of curvature (e.g., corannulene versus coronene) or if electron-withdrawing or -donating groups are part of the adsorbent. A negatively charged aromatic ring, the lithium phthalocyanine complex anion, [LiPc](-), introduces charge-induced dipole interactions into the adsorption process, resulting in a doubling of the binding energy of Li(2)Pc relative to corannulene. Experimental hydrogen adsorption results for Li(2)Pc, which are consistent with MD simulation results using chi-Li(2)Pc to simulate the adsorbent, suggest that only one side of the phthalocyanine ring is used in the adsorption process. The introduction of a tetrabutylammonium cation as a replacement for one lithium ion in Li(2)Pc has the effect of increasing the number of hydrogen molecules adsorbed from 10 (3.80 wt %) for Li(2)Pc to 24 (5.93 wt %) at 77 K and 45 bar, suggesting that both sides of the phthalocyanine ring are available for hydrogen adsorption. MD simulations of layered tetramethylammonium lithium phthalocyanine molecular systems illustrate that doubling the wt % H(2) adsorbed is possible via such a system. Ab initio calculations also suggest that layered or sandwich structures can result in significant reductions in the pressure required for hydrogen adsorption.

The ionisation state of a compound is a key parameter influencing the compound's activity as a drug, metabolite, pollutant, or other active chemical agent. Sulfhydrol compounds (thiols) tend to be considerably more acidic than their hydroxyl (alcohol) analogues. In this report, quantum chemical approaches previously used for the estimation of the aqueous pK a s of alcohols are applied to the estimation of the acidities of thiols. Acidity estimates obtained from the general-purpose SPARC calculational programme (S.H. Hilal, S.W. Karickhoff, and L.A. Carreira, Quant. Struct.-Act. Relat. 14, 348 (1995)) and the ACD/Labs PhysChem Suite v12 programme package are employed as benchmarks. Quantum chemical calculations were performed using both the semiempirical RM1 method and the density functional theory B3LYP/6-31 + G * method. The effectiveness of the SM5.4 and SM8 solvent models in estimating the aqueous-phase acidities was also evaluated. All of the approaches examined demonstrated strong correlations with the experimental acidity values.