Surface-Plasmon-Polaritons for Reversible Assembly of Gold Nanoparticles, In Situ Nanogap Tuning, and SERS.

A transportable reversible assembly of gold nanoparticles (AuNPs) in an aqueous environment addresses the need for in situ surafce-enhanced Raman spectroscopy (SERS) hotspot creation for biological applications. Usually, light-directed AuNP assembly methods use higher laser powers and surfactants and are, hence, unsuitable for biological applications. Here, surface plasmon polaritons-assisted dynamic assembly of AuNPs are demonstrated at laser power density as low as 100 nW µm-2 . The AuNP assembly with multiple controllable hotspots is generated in an Au-water interface for solution-based SERS measurements. The major advantage of the method is that the interparticle nanogap is tunable to achieve analyte and AuNP-specific optimum SERS enhancement. The SERS intensity is reproducible on multiple reassembly cycles and assembly attempts, proving repeatability in the produced nanogap pattern. The assembly experiments reveal the influence of AuNP surface charge and the resulting polarizability on the SPP forces. The developed system and method can detect sulforhodamine 101 (SR101) dye molecules at concentrations as low as 10-10  m. Further, the SERS measurements on double-stranded DNA suggest that the molecules are oriented in a fashion to expose adenosine to the enhanced field, leading to its dominance in the recorded spectra.

Modified Open Anterior Preperitoneal Repair.

Background and Objectives: Modified anterior preperitoneal (mAPP) repair for inguinal hernia (IH) was compared with Lichtenstein repair (LR) and laparoscopic transabdominal preperitoneal (TAPP) repairs. Methods: IH patients, after exclusions and subsequent matching for age, type, and extent of hernia, were assigned randomly for mAPP, LR or TAPP repair. The same surgical team performed all operations. Data of predefined endpoints for all the three groups were statistically compared. Results: One hundred thirty-five patients underwent mAPP, 91 patients LR, and 181 patients TAPP. The operating time for both unilateral and bilateral hernias in the mAPP group was significantly shorter than in LR and TAPP groups. mAPP patients were discharged in significantly less time than LR patients but later than TAPP patients. Postoperative visual analog scale (VAS) score at 24 hours in the mAPP patients was significantly less than LR but at 48 hours the difference was equivocal. But VAS score after mAPP at 24 and 48 hrs was more than in TAPP patients. However, the pain score across all the three groups was similar at 7 days. There was no surgical site infection (SSI) or mesh infection in any patient. Chronic postoperative inguinal pain was seen less often after mAPP than after LR but was least in TAPP patients. Recurrence across all the three groups was not much different. Conclusion: mAPP appears to be a better choice for open IH repair than LR and matches the advantages of Laparoscopic repairs.

New benzisoxazole derivative: A potential corrosion inhibitor for mild steel in 0.5 M hydrochloric acid medium -insights from electrochemical and density functional theory studies.

6-fluoro-3-(4-piperidinyl)-1,2-benzisoxazole. HCl (FPBH), a substituted benzisoxazole derivative, was prepared from isonipecotic acid and characterized using various spectroscopic techniques. Using electrochemical examinations such as potentiodynamic polarisation (PDP) and electrochemical impedance spectroscopic (EIS) technique, the corrosion mitigation capabilities of this compound for mild steel (MS) in 0.5 M HCl medium were investigated. Theoretical studies were performed using quantum chemical calculations and density functional theory (DFT). PDP results exhibited the mixed-type behavior of FPBH and showed a maximum efficiency of 94.5 % at 1 × 10-3 M. The development of a protective adsorbed layer of FPBH decreases the corrosion current density (icorr) and corrosion rate (CR). The EIS technique revealed that the rise in the charge transfer resistance (Rct) values and reduction in the thickness of the double-layer capacitance (Cdl) reflected the drop in corrosion rate. The adsorption of FPBH took place through physisorption by conforming Langmuir's isotherm. The DFT method was performed on the optimized structure of FPBH to get additional evidence on the action mode of FPBH with the metal surface.

Auxiliary Partial Orthotopic Liver Transplant as a Rescue Procedure for Acute Liver Failure with Extra-Small-for-Size Grafts: A Report of 2 Cases.

Auxiliary partial orthotopic liver transplant is a complex technique whereby a partial liver graft is transplanted in the orthotopic position, leaving behind a portion of the native liver. In acute liver failure, auxiliary partial orthotopic liver transplant serves as a rescue therapy and bridge for the native liver to regenerate. Auxiliary partial orthotopic liver transplant was initially considered a technically challenging procedure with inferior results versus orthotopic liver transplant. However, advancements in surgical techniques have led to improved results with auxiliary partial orthotopic liver transplant. Auxiliary partial orthotopic liver transplant is now increasingly accepted as a valid treatment option for acute liver failure. We present 2 cases of acute liver failure treated with auxiliary partial orthotopic liver transplant using an extra-small-for-size graft. The first case was a 12-year-old female patient who presented with druginduced acute liver failure and required an auxiliary partial orthotopic liver transplant with an extra-small left lobe graft (graft-to-recipient weight ratio of 0.45). The second case was a 23-year-old male patient with acute liver failure of unknown etiology who underwent an auxiliary partial orthotopic liver transplant with a small right lobe graft (graft-torecipient weight ratio of 0.5). In both cases, computed tomography liver volumetry was performed to determine the appropriate graft size for the recipient. Both patients underwent successful auxiliary partial orthotopic liver transplants, with good postoperative recovery. Follow-up examinations showed satisfactory liver function without evidence of graft failure or rejection. Auxiliary partial orthotopic liver transplant using extra-small grafts can be an effective treatment option for acute liver failure when no other suitable option exists, including as a rescue procedure for small grafts. However, careful patient selection and surgical planning are essential to ensure successful outcomes.

A Comparative Evaluation of Extended Total Extraperitoneal Repair Versus Standard Total Extraperitoneal Repair and Transabdominal Preperitoneal Repair of Inguinal Hernias.

Background and Objectives: Laparoscopic inguinal hernia repair (LIHR) includes transabdominal preperitoneal repair (TAPP), standard totally extraperitoneal repair (TEP), and now extended TEP (eTEP). However, there is still a paucity of well conducted, peer reviewed comparative studies regarding the advantages, if any, of eTEP. This study aimed to compare the data of eTEP repair with that of TEP and TAPP repair. Methods: Two hundred twenty patients were randomly assigned to one of three groups of eTEP (80), TEP (68), and TAPP (72) after matching for age, sex, and clinical extent of hernia. Permission of ethics committee was taken. Results: Comparison with TEP showed, mean operating time for eTEP was significantly longer in the first 20 patients, subsequently there was no difference. Conversion rates of TEP to TAPP was significantly higher. The other peroperative and postoperative parameters did not differ. Similarly, on comparison with TAPP, there was no difference in any of the parameters. eTEP, also had shorter operating time and less incidence of pneumoperitoneum when compared to published TEP and TAPP studies. Conclusion: All the three laparoscopic hernia approaches had similar outcomes. eTEP cannot be advocated as a substitute for TAPP or TEP.The choice of procedure should be the surgeon's choice. However, eTEP does combine the advantage of both TAPP, in the form of a large working space and of TEP, by being totally extraperitoneal. eTEP is also easier to learn and teach.

Late Hemorrhage Following Laparoscopic Cholecystectomy.

Background: Excruciating generalized abdominal pain with features suggestive of shock, at the end of the first or early second week after laparoscopic cholecystectomy (LC), is a frightening and formidable diagnostic predicament. This is because the early known complications like biliary leak or vascular injuries are unlikely diagnoses. Hemoperitoneum, is not usually considered, but instead more common occurrences like acute pancreatitis, choledocholithiasis, and sepsis are suspected. A delay in diagnosis and subsequent management of hemoperitoneum could have disastrous consequences. Case Studies: Two patients presented with hemoperitoneum, in the second week after laparoscopic cholecystectomy. The first was because of a leak from a pseudoaneurysm of the right hepatic artery and the other was a bleed from a subcapsular liver hemangioma as a part of Osler Weber Rendu syndrome. Initially, a clinical assessment in both the patients was diagnostically inconclusive. Ultimately the diagnosis could be made, based on computed tomography angiography and visceral angiography. In the second patient, a positive family history and genetic testing were helpful. The first patient was successfully managed by intravascular embolization, while the second patient was successfully managed conservatively with intraperitoneal drains and conservative management of comorbidities. Conclusions: The presentation is to generate awareness that hemorrhage could be a presentation, in the early second week, after LC. A common cause to be considered is a pseudo aneurysmal bleed. Secondary hemorrhage and other rare coincidental unassociated conditions could also be responsible for the hemorrhage. A high index of suspicion, and early and timely management are keys to a successful outcome.

COVID-19 and Clinical Trials: Current Challenges and Future Directions.

BACKGROUND: The outbreak of coronavirus disease (COVID-19) has posed a major threat to people's lives across the globe. It has drastically changed the way we perceive this world. A paradigm shift was observed globally as the world's emphasis shifted to testing, diagnosis, treatment, and developing a coronavirus cure. Clinical trials were also not untouched by this. The coronavirus pandemic has abhorrently affected the day-to-day clinical trial activities at sites. METHODS: The status of various ongoing clinical trials was assessed through a literature search, which also includes clinical trial portals. Our evaluations were based on these observations. RESULTS: Multiple challenges were present in clinical trials as recruitment, retention, the safety of trial subjects, protocol compliance, and this made the world to re-think to incorporate newer strategies and to cope with this untoward situation. CONCLUSION: Digitalization of clinical trials as virtual management of adverse events, remote monitoring visits, and web-based consulting with trial subjects are potential directions that can be applied to better manage clinical trials worldwide.

Refractive index and formaldehyde sensing with silver nanocubes.

We report the synthesis of Ag nanocubes by using a sodium sulfide assisted solvothermal method. Small edge-length nanocubes (32 and 44 nm) were obtained at 145 and 155 °C reaction temperature in the synthesis process. The refractive index sensitivity of synthesized nanocubes was investigated with an aqueous solution of glucose. The refractive index sensitivity of 161 nm per RIU was found in the colloidal dispersion of nanocubes. On the LSPR chip made by immobilization of nanocubes on the (3-aminopropyl)trimethoxysilane modified glass coverslip, the obtained sensitivity was 116 nm per RIU. Detection of formaldehyde in water and milk samples was also performed with nanocubes of edge-length of 44 nm. Formaldehyde detection was performed by utilizing the interaction of the aryl amine of 4-aminothiophenol immobilized on the nanocubes and electrophilic carbon atom of the formaldehyde. In water and in diluted milk, the formaldehyde sensitivity of 0.62 and 0.29 nm µM-1 was obtained, respectively.

A highly sensitive surface-enhanced Raman scattering substrate prepared on a hydrophobic surface using controlled evaporation.

In the present work, we report the fabrication of a surface-enhanced Raman spectroscopy (SERS) substrate on a simple and easily fabricable hydrophobic surface. The substrates are prepared by slow and fast evaporation of a droplet of silver nanoparticle suspension in water. The corresponding identifiers for two substrates are "s_evp" and "f_evp" respectively. It is found that the dried spot size is small on s_evp compared to that on f_evp. This also minimizes the coffee stain effect and enriches the spot in a better way on s_evp compared to f_evp. Consequently, using SERS experimentation on our lab-built setup, concentration as low as 2.5*10-12 M of rhodamine 6G molecules was detected on s_evp compared to 2.5 × 10-10 M on f_evp. The proposed s_evp SERS substrate is much easier to fabricate and easy to use compared to super-hydrophobic SERS substrates.

Effect of OH substitution in 3-benzylchroman-4-ones: crystallographic, CSD, DFT, FTIR, Hirshfeld surface, and energy framework analysis.

3-Benzylchroman-4-ones (homoisoflavanones) are oxygen-containing heterocycles with a sixteen-carbon skeleton. They belong to the class of naturally occurring polyphenolic flavonoids with limited occurrence in nature and possess anti-inflammatory, antibacterial, antihistaminic, antimutagenic, antiviral, and angioprotective properties. Recently, we reported the synthesis and anticancer activity studies of fifteen 3-benzylchroman-4-one molecules, and most of them were proven to be effective against BT549 and HeLa cells. In this work, we report the single-crystal X-ray crystallographic studies of two molecules 3-[(2-hydroxyphenyl)methyl]-3,4-dihydro-2H-1-benzopyran-4-one and 3-[(2,4-dimethoxyphenyl)methyl]-3,4-dihydro-2H-1-benzopyran-4-one. The single crystals were grown using a novel laser-induced crystallization technique. We observed that the 3-benzylchroman-4-one derivative bearing OH substitution at the 2' position adopted different conformation due to formation of dimers through O-H⋯O, and C-H⋯O intermolecular hydrogen bondings. The role of OH substitution in the aforementioned conformational changes was evaluated using density functional theory (DFT), Hirshfeld surface, energy framework and FTIR spectroscopy analysis. In addition, we have carried out a Cambridge Structural Database (CSD) study to understand the conformational changes using five analogue structures. X-ray crystallographic, computational, and spectroscopic studies of 3-benzylchroman-4-ones provided an insight into the role of substitution at benzyl moieties in stabilizing the three-dimensional (3D) structures.

Binding Motifs in the Naked Complexes of Target Amino Acids with an Excerpt of Antitumor Active Biomolecule: An Ion Vibrational Spectroscopy Assay.

The structures of proton-bound complexes of 5,7-dimethoxy-4H-chromen-4-one (1) and basic amino acids (AAs), namely, histidine (His) and lysine (Lys), have been examined by means of mass spectrometry coupled with IR ion spectroscopy and quantum chemical calculations. This selection of systems is based on the fact that 1 represents a portion of glabrescione B, a natural small molecule of promising antitumor activity, while His and Lys are protein residues lining the cavity of the alleged receptor binding site. These species are thus a model of the bioactive adduct, although clearly the isolated state of the present study bears little resemblance to the complex biological environment. A common feature of [1+AA+H]+ complexes is the presence of a protonated AA bound to neutral 1, in spite of the fact that the gas-phase basicity of 1 is comparable to those of Lys and His. The carbonyl group of 1 acts as a powerful hydrogen-bond acceptor. Within [1+AA+H]+ the side-chain substituents (imidazole group for His and terminal amino group for Lys) present comparable basic properties to those of the α-amino group, taking part to a cooperative hydrogen-bond network. Structural assignment, relying on the comparative analysis of the infrared multiple photon dissociation (IRMPD) spectrum and calculated IR spectra for the candidate geometries, derives from an examination over two frequency ranges: 900-1800 and 2900-3700 cm-1 . Information gained from the latter one proved especially valuable, for example, pointing to the contribution of species characterized by an unperturbed carboxylic OH or imidazole NH stretching mode.

Vibronic spectra of jet-cooled 1-methyl-2(1H)-quinolinone studied by Fluorescence spectroscopy and Quantum chemical calculation.

1-methyl-2(1H)-quinolinone (MeQone) forms the framework of several hundred quinolone alkaloid molecules, both natural and synthetic, which are being used in various biological applications. In this work, we present experimental and theoretical spectroscopic investigation on the MeQone in its ground and first electronic excited states. The vibronically resolved fluorescence excitation (FE) spectrum of MeQone is recorded within 700 cm-1 to the electronic origin under the supersonic jet-cooled condition. The dispersed fluorescence (DF) spectra for bands observed in the FE spectrum were also recorded. Bands observed in DF spectra were identified and assigned with the help of Density Functional Theory (DFT) calculated harmonic vibrational frequencies. Based on the assignments of bands in the ground electronic state and TD-DFT calculated frequencies for the first excited state, we have identified and successfully assigned the bands observed in FE spectrum. This study could be helpful to understand the photophysical properties of MeQone derivatives, the quinolone alkaloids.

Ab initio and NBO studies of methyl internal rotation in 1-methyl-2(1H)-quinolinone: effect of aromatic substitution to 1-methyl-2(1H)-pyridone.

1-methyl-2(1H)-quinolinone (MeQone) forms the framework of several hundred alkaloid molecules both natural and synthetic being used for various biological applications. From chemical structure point of view, the molecules can also be seen as an aromatic ring fused to 1-methyl-2(1H)-pyridone (1-MPY). In this work, we present theoretical investigations on internal rotation of methyl group in MeQone in light of 1-MPY. We looked into the change in the three-fold (V3) methyl internal rotation barrier resulted from the aromatic ring substitution to 1-MPY. The V3 term in two molecules were calculated using density functional theory and Hartree-Fock theory with different basis sets. MeQone has calculated V3 term (in S0 state) three times higher in magnitude compared with that of 1-MPY. The role of aromatic substitution in increase of V3 term is investigated using natural bond orbital (NBO) analyses. In the NBO analysis, it is found that the aromatic ring as highly delocalized π-system lowers the magnitude of hyperconjugation energy in MeQone compared with 1-MPY. This is due to the extension of delocalization of π-electrons to pyridone ring which lowers the orbital overlap. However, the Lewis energy increases substantially and make the overall barrier energy higher in MeQone compared with 1-MPY. From our study, we conclude that in the molecules such as 1-MPY and MeQone where the methyl group has two single bonds vicinal to it, the overall hyperconjugation energy is always barrier forming with nonlocal interactions playing significant role. Also, the Lewis energy plays the decisive role in barrier formation, and its magnitude can be tuned by tuning the π-electron delocalization. We have also looked into the change in methyl group conformation upon electronic excitation to S1 state. In 1-MPY, the methyl group rotated by 60° upon excitation whereas in MeQone, there was no conformational change. Strong π*-σ* interaction in LUMO in top-of-barrier conformation is responsible for the change in the methyl group conformation in 1-MPY, whereas same π*-σ* interaction in LUMO of minimum energy conformation results in unchanged excited state conformation in MeQone. Graphical abstract.

Intermolecular dissociation energies of 1-naphthol complexes with large dispersion-energy donors: Decalins and adamantane.

The ground-state intermolecular dissociation energies D0(S0) of supersonic-jet cooled intermolecular complexes of 1-naphthol (1NpOH) with the bi- and tricycloalkanes trans-decalin, cis-decalin, and adamantane were measured using the stimulated-emission-pumping/resonant two-photon ionization (SEP-R2PI) method. Using UV/UV holeburning, we identified two isomers (A and B) of the adamantane and trans-decalin complexes and four isomers (A-D) of the cis-decalin complex. For 1NpOH·adamantane A and B, the D0(S0) values are 21.6 ± 0.15 kJ/mol and 21.2 ± 0.32 kJ/mol, those of 1NpOH·trans-decalin A and B are 28.7 ± 0.3 kJ/mol and 28.1 ± 0.9 kJ/mol, and those of 1NpOH·cis-decalin A and B are 28.9 ± 0.15 kJ/mol and 28.7 ± 0.3 kJ/mol. Upon S0 → S1 electronic excitation of the 1NpOH moiety, the dissociation energies of adamantane, trans-decalin, and the cis-decalin isomer C change by <1% and those of cis-decalin isomers A, B, and D increase only slightly (1%-3%). This implies that the hydrocarbons are dispersively adsorbed to a naphthalene "face." Calculations using the dispersion-corrected density functional theory methods B97-D3 and B3LYP-D3 indeed predict that the stable structures have face geometries. The B97-D3 calculated D0(S0) values are within 1 kJ/mol of the experiment, while B3LYP-D3 predicts D0 values that are 1.4-3.3 kJ/mol larger. Although adamantane has been recommended as a "dispersion-energy donor," the binding energies of the trans- and cis-decalin adducts to 1NpOH are 30% larger than that of adamantane. In fact, the D0 value of 1NpOH·adamantane is close to that of 1NpOH·cyclohexane, reflecting the nearly identical contact layer between the two molecules.

Benchmark Experimental Gas-Phase Intermolecular Dissociation Energies by the SEP-R2PI Method.

The gas-phase ground-state dissociation energy D0(S0) of an isolated and cold bimolecular complex is a fundamental measure of the intermolecular interaction strength between its constituents. Accurate D0 values are important for the understanding of intermolecular bonding, for benchmarking high-level theoretical calculations, and for the parameterization of dispersion-corrected density functionals or force-field models that are used in fields ranging from crystallography to biochemistry. We review experimental measurements of the gas-phase D0(S0) and D0(S1) values of 55 different M⋅S complexes, where M is a (hetero)aromatic molecule and S is a closed-shell solvent atom or molecule. The experiments employ the triply resonant SEP-R2PI laser method, which involves M-centered (S0 → S1) electronic excitation, followed by S1 → S0 stimulated emission spanning a range of S0 state vibrational levels. At sufficiently high vibrational energy, vibrational predissociation of the M⋅S complex occurs. A total of 49 dissociation energies were bracketed to within ≤1.0 kJ/mol, providing a large experimental database of accurate noncovalent interactions.

Face, Notch, or Edge? Intermolecular dissociation energies of 1-naphthol complexes with linear molecules.

The stimulated-emission-pumping/resonant 2-photon ionization (SEP-R2PI) method was used to determine the intermolecular dissociation energies D0 of jet-cooled 1-naphthol(1NpOH)·S complexes, where S is a linear molecule (N2, CO, CO2, OCS, N2O, and ethyne) or symmetric-top molecule (2-butyne) that contains double or triple bonds. The dissociation energies D0(S0) are bracketed as follows: 6.68 ± 0.08 kJ/mol for S=N2, 7.7 ± 0.8 kJ/mol for CO, 12.07 ± 0.10 kJ/mol for CO2, 13.03 ± 0.01 kJ/mol for N2O, 14.34 ± 0.08 kJ/mol for ethyne, 15.0 ± 1.35 kJ/mol for OCS, and 29.6 ± 2.4 kJ/mol for 2-butyne. The minimum-energy structures, vibrational wavenumbers, and zero-point vibrational energies were calculated using the dispersion-corrected density functional theory methods such as B97-D3 and B3LYP-D3 with the def2-QZVPP basis set. These predict that N2 and CO are dispersively bound Face complexes (S bound to a naphthalene Face), while CO2, N2O, and OCS adsorb into the "Notch" between the naphthyl and OH groups; these are denoted as Notch complexes. Ethyne and 2-butyne form Edge complexes involving H-bonds from the -OH group of 1NpOH to the center of the molecule. The presence of a double or triple bond or an aromatic C=C bond within S does not lead to a specific calculated geometry (Face, Notch or Edge). However, a correlation exists between the structure and the sign of the quadrupole moment component Θzz of S: negative Θzz correlates with Face or Notch, while positive Θzz correlates with Edge geometries.

Comparative Evaluation of Dexmedetomidine and Pregabalin as Premedication Agent to Attenuate Adverse Hemodynamic and Stress Response in Patients Undergoing Laparoscopic Cholecystectomy.

BACKGROUND: Laparoscopic cholecystectomy is the most commonly performed laparoscopic procedure. The goal of anesthetic management is to minimize stress response and early discharge. Dexmedetomidine, and pregabalin have been used successfully to attenuate laryngoscopy and intubation response in various surgical procedures. AIM: To compare efficacy of pregablin and dexmedetomidine in attenuating hemodynamic and stress response. SETTING AND DESIGN: A prospective, double blind randomized trial comprising 130 ASA physical status class I and II patients posted for laparsoscopic cholecystectomy. MATERIALS AND METHODS: Patients were randomized in to Group A and Group B. Group A received intravenous dexmedetomidine in a dose of 1 ug.kg-1, through an infusion pump 20 min prior to induction of anaesthesia. Group B subjects received oral pregabalin 150 mg. Parameters observed were vitals, discharge time, cortisol level, side effects if any. RESULTS: Post intervention heart rate got reduced significantly in Group A and it remained low in comparison to baseline during whole peri-operative period. In Group B, immediate post-pneumoperitoneum heart rate, and post exubation heart rate was higher than baseline. Blood pressure (BP) decreased significantly post intervention in Group A which persisted till pneumoperitoneum. In Group B there was statistically significant rise in systolic, diastolic and mean blood pressure postpneumoperitoneum as compared to baseline blood pressure. Post-operative cortisol level was significantly higher than baseline values and the level is more in Group B. CONCLUSION: Intravenous dexmedetomidine is more effective than oral pregabalin in attenuating perioperative stress response.

Intermolecular dissociation energies of hydrogen-bonded 1-naphthol complexes.

We have measured the intermolecular dissociation energies D 0 of supersonically cooled 1-naphthol (1NpOH) complexes with solvents S = furan, thiophene, 2,5-dimethylfuran, and tetrahydrofuran. The naphthol OH forms non-classical H-bonds with the aromatic π-electrons of furan, thiophene, and 2,5-dimethylfuran and a classical H-bond with the tetrahydrofuran O atom. Using the stimulated-emission pumping resonant two-photon ionization method, the ground-state D 0(S 0) values were bracketed as 21.8 ± 0.3 kJ/mol for furan, 26.6 ± 0.6 kJ/mol for thiophene, 36.5 ± 2.3 kJ/mol for 2,5-dimethylfuran, and 37.6 ± 1.3 kJ/mol for tetrahydrofuran. The dispersion-corrected density functional theory methods B97-D3, B3LYP-D3 (using the def2-TZVPP basis set), and ωB97X-D [using the 6-311++G(d,p) basis set] predict that the H-bonded (edge) isomers are more stable than the face isomers bound by dispersion; experimentally, we only observe edge isomers. We compare the calculated and experimental D 0 values and extend the comparison to the previously measured 1NpOH complexes with cyclopropane, benzene, water, alcohols, and cyclic ethers. The dissociation energies of the nonclassically H-bonded complexes increase roughly linearly with the average polarizability of the solvent, α ¯ (S). By contrast, the D 0 values of the classically H-bonded complexes are larger, increase more rapidly at low α ¯ (S), but saturate for large α ¯ (S). The calculated D 0(S 0) values for the cyclopropane, benzene, furan, and tetrahydrofuran complexes agree with experiment to within 1 kJ/mol and those of thiophene and 2,5-dimethylfuran are ∼3 kJ/mol smaller than experiment. The B3LYP-D3 calculated D 0 values exhibit the lowest mean absolute deviation (MAD) relative to experiment (MAD = 1.7 kJ/mol), and the B97-D3 and ωB97X-D MADs are 2.2 and 2.6 kJ/mol, respectively.

Intermolecular dissociation energies of dispersively bound complexes of aromatics with noble gases and nitrogen.

We measured accurate intermolecular dissociation energies D0 of the supersonic jet-cooled complexes of 1-naphthol (1NpOH) with the noble gases Ne, Ar, Kr, and Xe and with N2, using the stimulated-emission pumping resonant two-photon ionization method. The ground-state values D0(S0) for the 1NpOH⋅S complexes with S= Ar, Kr, Xe, and N2 were bracketed to be within ±3.5%; they are 5.67 ± 0.05 kJ/mol for S = Ar, 7.34 ± 0.07 kJ/mol for S = Kr, 10.8 ± 0.28 kJ/mol for S = Xe, 6.67 ± 0.08 kJ/mol for isomer 1 of the 1NpOH⋅N2 complex, and 6.62 ± 0.22 kJ/mol for the corresponding isomer 2. For S = Ne, the upper limit is D0 < 3.36 kJ/mol. The dissociation energies increase by 1%-5% upon S0 → S1 excitation of the complexes. Three dispersion-corrected density functional theory (DFT-D) methods (B97-D3, B3LYP-D3, and ωB97X-D) predict that the most stable form of these complexes involves dispersive binding to the naphthalene "face." A more weakly bound edge isomer is predicted in which the S moiety is H-bonded to the OH group of 1NpOH; however, no edge isomers were observed experimentally. The B97-D3 calculated dissociation energies D0(S0) of the face complexes with Ar, Kr, and N2 agree with the experimental values within <5%, but the D0(S0) for Xe is 12% too low. The B3LYP-D3 and ωB97X-D calculated D0(S0) values exhibit larger deviations to both larger and smaller dissociation energies. For comparison to 1-naphthol, we calculated the D0(S0) of the carbazole complexes with S = Ne, Ar, Kr, Xe, and N2 using the same DFT-D methods. The respective experimental values have been previously determined to be within <2%. Again, the B97-D3 results are in the best overall agreement with experiment.