NH Bond Research Articles

Non-adiabatic dynamics of Rydberg-excited diethylamine

Femtosecond time-resolved photoelectron spectroscopy was employed to investigate the ultrafast non-adiabatic dynamics of diethylamine (DEA). Following the direct excitations of the two main conformational structures (i.e., TT and TG) of DEA to the 3p Rydberg states at 200 nm, DEA undergoes internal conversion to the 3s state with ∼68 fs, which is similar to previously relaxation pathways of several secondary and tertiary amines. Subsequent dynamics on the 3s Rydberg state evolves along the NH stretching coordinate and is then accompanied by the breaking of the NH bond in about 120 fs, rather than the cleavage of the NC, or CC bonds as well as the conformational transformations between the TT and TG conformers on the 3s states. Theoretically, we reveal the pre-dissociative nσ* character evolving along the NH stretching coordinate within the 3s state as DEA dissociates to yield H atom products. As contrasted to the well-known conformational NC bond rotation motions in systems such as tertiary amines, the non-adiabatic relaxation of the 3s state of DEA is predominantly characterized by the NH bond dissociation process.

A DFT approach for finding therapeutic potential of two dimensional (2D) graphitic carbon nitride (GCN) as a drug delivery carrier for curcumin to treat cardiovascular diseases

The density functional theory (DFT) analysis is used to predict the therapeutic potential of Graphitic carbon nitride (GCN) as a medicinal carrier for curcumin for the treatment of cardiovascular diseases. To evaluate the drug transport capacity of GCN, the electronic, ground, and excited-state properties of curcumin, GCN, and the GCN-curcumin-complex were investigated. The adsorption energy of the GCN-curcumin-complex is higher in the gas phase (−0.25 eV) than in the aqueous phase (−0.09 eV), implying that the GCN-curcumin-complex is more stable in the gas phase. Weak NH bonds anchored the curcumin at GCN surface. The GCN-curcumin-complex has a higher dipole moment in the aqueous medium (2.37 D) than in the gas phase (1.36 D) which aids in the efficient transport of the drug through biological systems. Molecular electrostatic potential and frontier molecular orbitals revealed that during excitation, curcumin behaves as a HOMO, transferring charge to the LUMO (GCN). The charge decomposition analysis, which determines the highest overlap between the curcumin and GCN orbitals, was also employed to investigate the charge transfer process. For several transitions from the donor to the acceptor, Natural bond orbital (NBO) analysis revealed that charge was transferred between the curcumin and GCN molecules. For the GCN-curcumin-complex, excited-state calculations show that λmax is redshifted by 131 nm. The redshift for the GCN-curcumin-complex in the solvent phase is 149 nm. The theoretically generated spectra match experimentally observed spectra quite well. Moreover, the in silico infrared spectra of GCN and Curcumin is also close to the experimental spectra. For the graphical explanation of various excited states, electron-hole and photoinduced electron-transfer analysis are performed. The Photoinduced electron transfer (PET) mechanism perceives quenching of fluorescence because of an interaction. Moreover, GCN +1/−1 showed little structural change and produces stable curcumin complexes. All findings indicated that GCN has substantial therapeutic potential as a carrier for curcumin in cardiovascular disease cure. Researchers will be motivated to investigate alternative 2D nanomaterials for drug delivery applications due to this theoretical study.

Collision site effect on the radiation dynamics of cytosine induced by proton

By combing the time-dependent density functional calculations for electrons with molecular dynamics simulations for ions (TDDFT-MD) nonadiabatically in real time, we investigate the microscopic mechanism of collisions between cytosine and low-energy protons with incident energy ranging from 150 eV to 1000 eV. To explore the effects of the collision site and the proton incident energy on irradiation processes of cytosine, two collision sites are specially considered, which are N and O both acting as the proton receptors when forming hydrogen bonds with guanine. Not only the energy loss and the scattering angle of the projectile but also the electronic and ionic degrees of freedom of the target are identified. It is found that the energy loss of proton increases linearly with the increase of the incident energy in both situations, which are 14.2% and 21.1% of the incident energy respectively. However, the scattering angles show different behaviors in these two situations when the incident kinetic energy increases. When proton collides with O, the scattering angle of proton is larger and the energy lost is more, while proton captures less electrons from O. The calculated fragment mass distribution shows the high counts of the fragment mass of 1, implying the production of H+ fragment ion from cytosine even for proton with the incident energy lower than keV. Furthermore, the calculated results show that N on cytosine is easier to be combined with low-energy protons to form NH bonds than O.

Multi-sites N-halamine antibacterial agent loaded on mesoporous silica nanoparticles with pH stimulus response

A bactericidal composite material contains a new type of N-halamine with three high bactericidal sites, and loaded the N-halamine in mesoporous silica nanoparticles (MSN), used ZnO quantum dots (ZnO QDs) as a capping gate for pH stimulus response. The N-halamine precursor NDAM was prepared by the amidation reaction of 2,5-dioxo-1,3-diazolidin-4-ylacetic acid and methacrylamide, which contains one imide and two amides NH bonds. After chlorination, three NH bonds were converted into three N-halamine sites, and the oxidative chlorine content was greatly increased. ZnO QDs have the ability to respond to pH stimuli and play a synergistic antibacterial effect with multi-site N-halamine. The antibacterial activity of MSN-AA-NDAM@ZnO nanoparticles against Gram-negative bacteria (E. coli) and Gram-positive bacteria (S. aureus) were studied by bacterial experiments. Compared with the single components (MSN-AA-NDAM-Cl and MSN@ZnO), the antibacterial activity of MSN-AA-NDAM@ZnO nanoparticles showed stronger antibacterial activity due to the synergistic bactericidal effect. This pH-responsive N-halamine bactericidal material provides a new idea in the field of antibacterial and has great application potential.

Excited-state proton transfer in a 2-aminopyridine dimer: a surface hopping study.

We present a theoretical investigation of the excited-state intermolecular proton transfer process in a 2-aminopyridine dimer. Previous experimental and theoretical studies on this doubly hydrogen bonded system have attributed an ultrafast 50 fs timescale to the process at low excitation wavelengths and have shown that it involves access to the charge transfer (CT) states of the dimer. We have carried out a trajectory-based surface hopping study of the proton transfer process. To this end, we have further studied the key intersections between locally excited (LE) and CT states that facilitate the proton transfer as well as the eventual ground state return at the XMS-CASPT2 level of theory. The dynamical simulations to investigate the charge transfer-driven event are performed at both the XMS-CASPT2 and TDDFT levels of theory. Trajectories are initiated from the excited states that are either already of CT character or become so upon a short extension of the NH bond. This kind of dynamics is found to be ultrafast with a timescale of about 100 fs, where the dimer rapidly accesses the LE/CT intersection regions en route to single proton transfer. After the transfer, some trajectories are also able to reach the ground state as well through a non-adiabatic transition. In contrast, trajectories that are initiated on an LE state remain on states of that character and do not show proton transfer. However, additionally providing 3 or 4 quanta of initial excitation to the NH stretch was found to promote CT state-driven proton transfer in the dimer.

A new supramolecular bonding motif involving NH bonds of ammonium salts and macrocycles derived from platinum corners and butadiynediyl linkers.

CuI catalyzes reactions of cis-(R2C(CH2PPh2)2)Pt(CCCCH)2 and cis-(R2C(CH2PPh2)2)PtI2 in secondary amine solvents HNR'2 to give the title adducts [(R2C(CH2PPh2)2)Pt(CCCC)]4·(H2NR'2+I-)n (R/R'/n = Me/Et/1, Me/((CH2CH2)2O)0.5/3, Et/Et/1, Et/CH2CHCH2/1; 92-42%). Crystal structures of these or closely related species establish folded Pt4 cores containing ammonium cation guests, with NH/ and NCH/CC hydrogen bonding. DOSY NMR experiments show that the host/guest relationship can be maintained in solution.

Computational study of interactions of the uracil molecule with the F- and [formula omitted] hard anions

We report the first computational study on anion clusters of uracil with F- and O2-using the B3LYP, B3LYP-GD3 methods with the aug-cc-pVnZ basis sets, n = 2–5. In each cluster, the anion selectively abstracts a proton from a specific NH bond in uracil. The transferred proton forms an incipient chemical bond with the anion while the transferred proton becomes hydrogen bonded to the uracil moiety. Most of the anion’s negative charge is transferred to uracil while the electron-spin density is redistributed among the oxygen atoms in O2-. We identified two pathways for dissociation and vibrationally induced proton transfer within each complex. There are large red shifts in frequencies and massive increase in intensities of the IR stretches in the protonated anions within the clusters. These new findings advance our knowledge about interactions of O2-with nucleotide bases and provide predictions for IR spectroscopic detection of the O2- uracil cluster.

Thermal aging of acrylic-urethane network: Kinetic modeling and end-of-life criteria combined with mechanical properties

This study addresses the multiscale analysis of acrylic urethane networks (AUN). To establish the kinetic model for predicting AUN oxidation, this study considered the pure thermal oxidation of AUN at 160, 180, and 200 °C. Chemical changes were monitored using infrared spectroscopy. These indicated the presence of an imide, presumably generated from the oxidation of CH2 at the α-position of nitrogen. On the macromolecular and macroscopic scales, oxidation was shown to induce predominant crosslinking, leading to a drop in toughness (i.e., embrittlement). The novel kinetic model of AUN thermal aging was developed from a mechanistic scheme previously established for polyamide 11, by adding some extra paths of thermolytic alkyl radical formation, oxidative NH bonds decomposition and coupling of aminyl radicals.

Hydrogen generation from hydrazine on N4 moieties graphene embedded by vanadium metal, DFT calculation

In this article, the catalytic effect of the VN4 on graphene has been studied for the decomposition of hydrazine (N2H4) with Density Functional Theory (DFT) calculations using DFT-D3 in the method of Grimme. The adsorb energy, a Bader charge transfer, charge density difference, and partial density of states were examined. Hydrazine decomposition is investigated in two different ways; the NN bond cleavage for N2H4→NH2+NH2 reaction and the NH bond cleavage for N2H4→N2H3+H to produce hydrogen production. According to our result, the gauche conformer of hydrazine is the most stable formation on the modified graphene surface. The interaction of hydrazine molecule with the surface is chemical adsorption through adding V impurity. The NN bond split for V embedded surface has lower activation energy than that of the NH bond cleavages. It is promising to investigate hydrogen generation from hydrazine on the high-performance graphene-like catalyst.

A label-free electrochemical immunosensor for rapid detection of salmonella in milk by using CoFe-MOFs-graphene modified electrode

The presence of Salmonella in food has been a serious threat to human health all over the world. Herein, a novel electrochemical immunosensor based on CoFe-MOFs-graphene nanocomposite was constructed to detect Salmonella in milk. The synergy of the large specific surface area and high porosity of CoFe-MOFs and the good electrical conductivity of graphene materials greatly enhanced the current signal of the nanocomposite. Gold nanoparticles were modified on CoFe-MOFs-graphene hybrids by a simple electrodeposition method. Anti-Salmonella antibody was immobilized onto the surface of the constructed electrode through the formation of a stable Au–NH2 bond. Scanning electron microscopy was employed to reveal the structure of the CoFe-MOFs-graphene nanocomposite, and the elements of the nanocomposite were observed by energy-dispersive X-ray spectroscopy. In addition, Fourier transform infrared (FT-IR) and X-ray powder diffraction (XRD) were used to analyze the structure of related materials. Under optimal experimental parameters, the constructed immunosensor detected a wide linear range of Salmonella from 2.4 × 102 CFU mL−1 to 2.4 × 108 CFU mL−1 with a detection limit of 1.2 × 102 CFU mL−1 (S/N = 3). The immunosensor showed good stability, selectivity, and reproducibility. The designed immunosensor provides a new strategy for the rapid detection of foodborne pathogens.

Crystal structure, Hirshfeld surfaces and vibrational studies of tetrachlorocobaltate hybrid perovskite salts NH3(CH2)nNH3CoCl4 (n = 4, 9)

Organic-inorganic hybrid perovskites NH3(CH2)nNH3CoCl4 (n = 4, 9) single crystals are prepared by solution precipitation method. Single crystal X-ray diffractions are performed. Both compounds crystallized in the centrosymmetric triclinic P-1 (Z = 2) space group; the determined parametrs for the novel salt NH3(CH2)9NH3CoCl4 are: a = 7.3113(4) Å, b = 10.2373(5) Å, c = 12.4701(9) Å; α = 112.323(2)°, β = 92.441(2)°, γ = 93.452(3)°, V = 859.68(9) Å3. The structure consists of the anions CoCl42− which form unassociated zero dimensional tetrahedral structure resemble to quantum dot show alternating up and down orientations relative to the c-axis that are sandwitched between layers of the diammonium organic chains. Hydrogen bonds NH…Cl are connecting organic and inorganic layer. The Hirshfeld surface analyzes are performed to compare the importance of hydrogen bonding contacts in the two hybrid compounds. The V/Z ratio on linear evolution versus n, number of CH2 groups in organic chains (n = 3–9) presents a minimal value at n = 5, corresponding to monoclinic symmetry of NH3(CH2)5NH3CoCl4. Besides, the vibrational modes analyzes are developed based on the theoretical group method considering the structural data obtained on +NH3(CH2)nNH3+ cations and CoCl42− anions. This to study the characteristic bands observed at room temperature in Infrared (250–4000 cm−1) and Raman (50–500 cm−1) spectra of these compounds.

Improvement of sludge dewaterability by energy uncoupling combined with chemical re-flocculation: Reconstruction of floc, distribution of extracellular polymeric substances, and structure change of proteins

This study innovatively combines energy uncoupling and chemical re-flocculation helped to accelerate residual sludge dewatering. Ferric chloride (FeCl3) and 3, 3′, 4′, 5-tetrachlor-osalicylanilide (TCS) were employed as the flocculant and uncoupler, respectively. The results showed that the specific resistance to filtration (SRF) and the water content of sludge filtered cake fell dramatically from 11 × 1012 m/kg and 80.2% to 1.1 × 1012 m/kg and 77.1% respectively, when the addition of TCS ranged from 0 to 0.12 g/g VSS with flocculation conditioning. The distribution of sludge extracellular polymeric substance (EPS) was altered radically after adding TCS, leading to the collapse and fragmentation of EPS, causing the reduction and formation of fragmentized sludge flocs. Meanwhile, the stretching and deformation vibrations of CO and NH bonds suggested the strong attack between TCS and EPS proteins, while variations of the main secondary structures of protein (i.e. α-helix, β-sheet and random coil) indicated the loose structure of proteins and enhanced hydrophobicity. Consequently, the cracked and loose structure of residual sludge resulted in the release of bound water. After TCS addition combined with chemical re-flocculation, the channels of sludge water discharge were widened, guaranteeing the discharge of sludge water. Therefore, the sludge dewaterability was elevated under the energy uncoupling combined with chemical re-flocculation. As well, the application of TCS would not destroy sludge cells, in which bioenergy (sludge carbon source) could be retained and effectively utilized in the subsequent disposal process. The findings reported here not only widen our perception of the energy uncoupling technology, but also encourage researchers to explore both effective and economic methods on the basis of energy uncoupling, aiming to achieve high-efficiency of reduction and dewatering in the future.

Er:YAG Laser Cleaning of Painted Surfaces: Functional Considerations to Improve Efficacy and Reduce Side Effects

The restoration of paintings always involves the removal of darkened superficial layers, which are mainly due to dust deposition and aged varnishes. As cleaning is an irreversible and invasive treatment, physical methods (i.e., laser cleaning) instead of chemical ones are frequently suggested to reduce side effects on pictorial layers. Among the most employed laser systems, the free-running Er:YAG laser is considered very suitable for fine arts cleaning. This laser works at 2.94 μm, at which only –OH and –NH bonds in molecules are excited. This character can become a disadvantage when pigments with these functional groups are present. To understand the potential of the Er:YAG laser in such situations or in the presence of degradable pigments, the effectiveness of varnish removal from paintings prepared with egg yolk as the binder and cinnabar and lead white as the pigments were systematically investigated. Different cleaning conditions were used, and a hyperspectral sensor was innovatively used as a rapid, in situ and non-destructive technique to assess the effects of laser ablation, besides microscopic analysis. Though results obtained show all these pigments are sensitive to this laser radiation, satisfactory cleaning can be achieved without damaging the pictorial layer. The best cleaning conditions were 0.5 W of power (50 mJ and 10 Hz for energy and frequency), with 2-propanol as the wetting agent.

Complexes of 1,3-Diisobutyl Thiourea with Copper(I), Zinc(II) and Mercury(II): Their Antioxidant and Antibacterial Evaluation

The reaction of 1,3-Diisobutyl thiourea (Tu) with metal salts, {[CuX (X = Cl, I)], [ZnCl2] and [HgI2] in an appropriate stoichiometric ratio afforded the corresponding metal complexes [Tu2CuCl] (1), [Tu3CuI] (2), [Tu2ZnCl2] (3) and [Tu2HgI2] (4) in good yields. The FT-IR data show typically broad signals (3278–3288 cm−1) attributed to the involvement of NH bonds in extensive hydrogen bonding. The structures of complexes were proposed based on a spectroscopic data set. Compounds 1 and 2 were additionally characterized by single-crystal X-ray analysis. Complexes 1–4 were tested for their free radical scavenging efficiency using 2,2-diphenyl-1-picrylhydrazyl free radical (hereafter abbreviated as DPPH). The free radical scavenging activity was a function of decrease in the resultant absorption of DPPH solution after the mixing of an appropriate concentration of the respective complex. The activity of complexes was determined to be dose dependent and increased concentration of the complex resulted in improved antioxidant activity. Compound 1 was found to be the most efficient, with 79.9% free radical scavenging activity. Complexes were also tested for their efficiency against selected strains of bacteria (E. coli, S. flexneri, S. typhi, and P. aeruginosa) and the activities were compared to commercially available standard drug cephradine. Compound 1 was more active against P.aeruginosa (ZI 13.25), while compound 4 was found to be more active against E. coli (ZI 11.0), S. flexneri (ZI 11.2), and S. typhi (ZI 10.5).

The effect of mixed soft segment on the microstructure of thermoplastic polyurethane

AbstractIn this work, we fixed the hard segment content (Ch%) and synthesized thermoplastic polyurethane (TPU) elastomers with one‐soft segment (HTPB‐PU, PTMG‐PU, and PCL‐PU) and bi‐soft segment (PTMG‐HPU and PCL‐HPU), using 4,4′‐diphenylmethane diisocyanate, 1,4‐butanediol, and different oligomer diols as raw materials. This work was used to explore the impact of two polar diols (polytetrahydrofuran diol [PTMG]; polycaprolactone diol [PCL]) of the hydroxy‐terminated polybutadiene (HTPB)‐based TPU on the microstructure and macroscopic properties. Using Fourier transform infrared spectroscopy, X‐ray diffraction, and differential scanning calorimetry to characterize TPU, the results showed that the introduction of PCL was better than PTMG in promoting microphase mixing and crystallization, and reducing microphase separation. This result was closely related because the carbonyl group in PCL was stronger than the ether bond in PTMG in forming hydrogen bonds with ─NH bond. Through mechanical test and isopropyl alcohol (IPA) resistance test, the results showed that HTPB‐based TPU with PCL (PCL‐HPU) significantly improved tensile strength and elongation at break, and only a small reduction of Young's modulus was observed. PCL‐HPU had the best retention of the IPA resistance of HTPB‐based TPU.

Nickel‐Catalyzed Suzuki‐Miyaura Cross‐Coupling Involving C−O Bond Activation

AbstractAn efficient Suzuki‐Miyaura cross‐coupling reaction of ortho‐phenoxy‐substituted aromatic amides with aryl boronates is described. The use of LiOtBu is crucial for the success of the reaction. An amidate anion, which is formed through deprotonation of the amide NH bond by LiOtBu, functions as a directing group to activate a C−O bond.

Aging microplastics in wastewater pipeline networks and treatment processes: Physicochemical characteristics and Cd adsorption

Despite a wealth of information on removal of the microplastics (MPs) in wastewater treatment plants (WWTPs), little attention has been paid to how wastewater treatment process affect the MP physicochemical and adsorption characteristics. In this study, changes in physicochemical property of three MPs, i.e. polyamide (PA), polyethylene (PE) and polystyrene (PS) through the wastewater pipeline, grit and biological aeration tanks were investigated. The results show that compared with virgin MPs, the treated MPs have higher specific surface area and O content, and lower C and H contents, and glass transition temperature, implying that the three treatments cause the chain scission and oxidation of the MPs. Cd adsorption capacities of the MPs are higher than the corresponding virgin MPs after sulfidation in the pipeline (SWPN) and biological treatment in aeration tank (BTAT). Pearson correlation analysis shows that the increase is mainly resulted from the enhancement of the O-containing groups on the MPs. However, Cd adsorption capacities of the MPs decrease after mechanical abrasion in grit tank (MAGT), corresponding to the decrease in carbonyl index. Two dimensional FTIR correlation spectroscopy demonstrates that the NH bond in the PA plays a more important role than CH bond in the adsorption of Cd, but only change of the CH bond is found in the PE and PS. The findings provide new insights into the effect of WWTPs on the MP aging and physicochemical characteristics.

Catalytic properties of nano-brass clusters: A density functional theory study

Brass (Cu-Zn) alloys are widely used as industrial materials. The structural and electronic properties of Cu-Zn clusters have been reported in theory recently [(Liu and Cheng, 2019); Journal of Cluster Science 2020, 31, 601–607], and the works have attracted intense research interest both experimentally and theoretically. However, to our knowledge the catalytic properties of the Cu-Zn clusters have not been analyzed. Here, we carry out our explorations of the catalytic properties of the selected Cu-Zn superatoms related to their geometric structures and stability. First, the global minimum structures of CuxZny (x + y = 14) alloy clusters are searched by an unbiased global method of genetic algorithm directly using the DFT functional. Among them, the spherical Cu8Zn6 and Cu10Zn4 satisfy magic numbers of the Jellium model and are two stable metal superatoms in this cluster series. Then, electrostatic potential surfaces of the brass clusters are analyzed, and the calculated results show that such alloy superatom has remarkable σ-holes with positive potential regions. Moreover, these electron-deficient regions can be considered as interaction sites with some Lewis bases. When a Lewis base CO gas molecule is attached to the alloy superatoms, we found that the CO bond distance become slightly elongated and its stretching frequency presents a significant red-shift. This is because that delocalized electrons of brass superatoms transfer towards the anti-bond π orbitals of CO molecule. Hence, these clusters may serve as potential catalysts for the covalent bond activation. However, the NH bond lengths of the clusters upon the NH3 adsorption are in accordance with that of the free NH3, and the analysis shows that the classical metals bind the NH3 molecule via donor interactions.

Insight into adsorption mechanism of Congo red dye onto Bombax Buonopozense bark Activated-carbon using Central composite design and DFT studies

In this study, a novel activated-carbon was prepared from Bombax Buonopozense (AC-BBP) and used for the adsorption of Congo red (CR) from aqueous solution and the prepared material was characterized by FTIR, XRD, TGA, SEM, elemental analysis and BET. Central Composite Design (CCD) was applied to optimize the medium conditions for the maximum removal of CR from aqueous solution and the optimization has been able to establish a quadratic mathematical model using three main factors varied from level (-1) to (+1) such as adsorbent dose (0.005 to 0.010 g), pH (7 to 9) and contact time (25 to 45 min), with an R2=98.73, a CV% =1.05 and an AP=27.79. The optimal conditions of the adsorption system were selected to be an adsorbent dosage of AC-BBP (0.117 g/L), solution pH (7.87) and a contact time of 29 min. These optimal conditions achieve the removal efficiency of CR is 86.12% from water using AC-BBP. The Langmuir isotherm is a good predictor of the experimental adsorption of Congo red with an adsorption capacity of 510.2 mg/g. The pseudo-second-order kinetic model shows a good fit with a correlation coefficient of R2> 0.99. Thermodynamic parameters were evaluated at 293 K and the results show a negative values of Gibbs free energy (-8.82 kJ/mol), indicating that the adsorption process was endothermic in nature. Moreover, Density functional theory (DFT) calculations were applied to understand the adsorption mechanism of the Congo red dye onto AC-BBP. The results shows that the groups of SO3− and N = N in CR are donating charge parts while the CH and NH bonds are an attracting electron or charge parts from the AC-BBP.

Vibrational Energy Flow in the Uracil-H2O Complexes.

In the uracil-H2O complex, the vibrational energy initially stored in the OH(v = 1) stretch efficiently transfers to the first overtone-bending mode under a near-resonant condition. The relaxation of the overtone vibration redistributes its energy to uracil and the two hydrogen bonds in the intermolecular zone, which consists of the OH bond and the bonds between nearby C, N, O, and H atoms of uracil. The uracil NH bond and the hydrogen bond it formed with the H2O molecule, N-H···O, store the major portion of the energy released by the relaxing bending mode, thus forming a localized hot band in the intermolecular zone. Energy transfer to the bonds beyond the zone is found to be not significant. The excited uracil NH is found to transfer its energy to the bending mode, thus indicating that the hydrogen bond of N-H···O is the principal energy pathway in both directions. In the presence of efficient near-resonant energy transfer pathways, the time evolution of the centers of mass distance shows the phenomenon of beats. One global and two different local minima energy structures are considered. The results of energy transfer do not differ significantly, suggesting that the two hydrogen bonds in all three structures have similar contributions to the energy transfer.