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Columbia Engineers Develop Light-Controlled Molecular Devices

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Saturday, March 16, 2024

Leveraging light to control electronic properties, Columbia Engineering’s new single-molecule devices with direct metal-metal contacts mark a significant advancement in molecular electronics, promising enhanced miniaturization and efficiency in electronic components. Credit: Venkatraman labIn a recent study published in Nature Communications, researchers from Columbia Engineering have announced the creation of highly conductive, tunable single-molecule devices in which the molecule is attached to leads by using direct metal-metal contacts. Their novel approach uses light to control the electronic properties of the devices and opens the door to broader use of metal-metal contacts that could facilitate electron transport across the single-molecule device.The challengeAs devices continue to shrink, their electronic components must also be miniaturized. Single-molecule devices, which use organic molecules as their conductive channels, have the potential to resolve the miniaturization and functionalization challenges faced by traditional semiconductors. Such devices offer the exciting possibility of being controlled externally by using light, but — until now – researchers have not been able to demonstrate this.“With this work, we’ve unlocked a new dimension in molecular electronics, where light can be used to control how a molecule binds within the gap between two metal electrodes,” said Latha Venkataraman, a pioneer in molecular electronics and Lawrence Gussman Professor of Applied Physics and professor of chemistry at Columbia Engineering. “It’s like flipping a switch at the nanoscale, opening up all kinds of possibilities for designing smarter and more efficient electronic components.” The approachVenkataraman’s group has been studying the fundamental properties of single-molecule devices for almost two decades, exploring the interplay of physics, chemistry, and engineering at the nanometer scale. Her underlying focus is on building single-molecule circuits, a molecule attached to two electrodes, with varied functionality, where the circuit structure is defined with atomic precision.Her group, as well as those creating functional devices with graphene, a carbon-based two-dimensional material, have known that making good electrical contacts between metal electrodes and carbon systems is a major challenge. One solution would be to use organo-metallic molecules and devise methods to interface electrical leads to the metal atoms within the molecule. Towards this goal, they decided to explore the use of organo-metallic iron-containing ferrocene molecules, which are also considered to be tiny building blocks in the world of nanotechnology. Just like LEGO pieces can be stacked together to create complex structures, ferrocene molecules can be used as building blocks to construct ultra-small electronic devices. The team used a molecule terminated by a ferrocene group comprising two carbon-based cyclopentadienyl rings that sandwich an iron atom. They then used light to leverage the electrochemical properties of the ferrocene-based molecules to form a direct bond between the ferrocene iron center and the gold (Au) electrode when the molecule was in an oxidized state (i.e. when the iron atom had lost one electron). In this state, they discovered that ferrocene could bind to the gold electrodes used to connect the molecule to the external circuitry. Technically, oxidizing the ferrocene enabled the binding of a Au0 to an Fe3+ center.“By harnessing the light-induced oxidation, we found a way to manipulate these tiny building blocks at room temperature, opening doors to a future where light can be used to control the behavior of electronic devices at the molecular level,” said the study’s lead author Woojung Lee, who is a Ph.D. student in Venkararaman’s lab.Potential impactVenkataraman’s new approach will enable her team to extend the types of molecular terminations (contact) chemistries they can use for creating single-molecule devices. This study also shows the ability to turn on and off this contact by using light to change the oxidation state of the ferrocene, demonstrating a light-switchable ferrocene-based single-molecule device. The light-controlled devices could pave the way for the development of sensors and switches that respond to specific light wavelengths, offering more versatile and efficient components for a wide range of technologies.The teamThis work was a collaborative effort involving synthesis, measurements, and calculations. The synthesis was done primarily at Columbia by Michael Inkpen, who was a post-doc in the Venkataraman group and is now an assistant professor at the University of Southern California. All the measurements were made by Woojung Lee, a graduate student in the Venkataraman group. The calculations were performed both by graduate students in the Venkataraman group and by collaborators from the University of Regensburg in Germany.What’s nextThe researchers are now exploring the practical applications of light-controlled single-molecule devices. This could include optimizing device performance, studying their behavior under different environmental conditions, and refining additional functionalities enabled by the metal-metal interface.Reference: “Photooxidation driven formation of Fe-Au linked ferrocene-based single-molecule junctions” by Woojung Lee, Liang Li, María Camarasa-Gómez, Daniel Hernangómez-Pérez, Xavier Roy, Ferdinand Evers, Michael S. Inkpen and Latha Venkataraman, 16 February 2024, Nature Communications.DOI: 10.1038/s41467-024-45707-z

In a recent study published in Nature Communications, researchers from Columbia Engineering have announced the creation of highly conductive, tunable single-molecule devices in which the...

Single Molecule Device

Leveraging light to control electronic properties, Columbia Engineering’s new single-molecule devices with direct metal-metal contacts mark a significant advancement in molecular electronics, promising enhanced miniaturization and efficiency in electronic components. Credit: Venkatraman lab

In a recent study published in Nature Communications, researchers from Columbia Engineering have announced the creation of highly conductive, tunable single-molecule devices in which the molecule is attached to leads by using direct metal-metal contacts. Their novel approach uses light to control the electronic properties of the devices and opens the door to broader use of metal-metal contacts that could facilitate electron transport across the single-molecule device.

The challenge

As devices continue to shrink, their electronic components must also be miniaturized. Single-molecule devices, which use organic molecules as their conductive channels, have the potential to resolve the miniaturization and functionalization challenges faced by traditional semiconductors. Such devices offer the exciting possibility of being controlled externally by using light, but — until now – researchers have not been able to demonstrate this.

“With this work, we’ve unlocked a new dimension in molecular electronics, where light can be used to control how a molecule binds within the gap between two metal electrodes,” said Latha Venkataraman, a pioneer in molecular electronics and Lawrence Gussman Professor of Applied Physics and professor of chemistry at Columbia Engineering. “It’s like flipping a switch at the nanoscale, opening up all kinds of possibilities for designing smarter and more efficient electronic components.”

The approach

Venkataraman’s group has been studying the fundamental properties of single-molecule devices for almost two decades, exploring the interplay of physics, chemistry, and engineering at the nanometer scale. Her underlying focus is on building single-molecule circuits, a molecule attached to two electrodes, with varied functionality, where the circuit structure is defined with atomic precision.

Her group, as well as those creating functional devices with graphene, a carbon-based two-dimensional material, have known that making good electrical contacts between metal electrodes and carbon systems is a major challenge. One solution would be to use organo-metallic molecules and devise methods to interface electrical leads to the metal atoms within the molecule. Towards this goal, they decided to explore the use of organo-metallic iron-containing ferrocene molecules, which are also considered to be tiny building blocks in the world of nanotechnology. Just like LEGO pieces can be stacked together to create complex structures, ferrocene molecules can be used as building blocks to construct ultra-small electronic devices. The team used a molecule terminated by a ferrocene group comprising two carbon-based cyclopentadienyl rings that sandwich an iron atom. They then used light to leverage the electrochemical properties of the ferrocene-based molecules to form a direct bond between the ferrocene iron center and the gold (Au) electrode when the molecule was in an oxidized state (i.e. when the iron atom had lost one electron). In this state, they discovered that ferrocene could bind to the gold electrodes used to connect the molecule to the external circuitry. Technically, oxidizing the ferrocene enabled the binding of a Au0 to an Fe3+ center.

“By harnessing the light-induced oxidation, we found a way to manipulate these tiny building blocks at room temperature, opening doors to a future where light can be used to control the behavior of electronic devices at the molecular level,” said the study’s lead author Woojung Lee, who is a Ph.D. student in Venkararaman’s lab.

Potential impact

Venkataraman’s new approach will enable her team to extend the types of molecular terminations (contact) chemistries they can use for creating single-molecule devices. This study also shows the ability to turn on and off this contact by using light to change the oxidation state of the ferrocene, demonstrating a light-switchable ferrocene-based single-molecule device. The light-controlled devices could pave the way for the development of sensors and switches that respond to specific light wavelengths, offering more versatile and efficient components for a wide range of technologies.

The team

This work was a collaborative effort involving synthesis, measurements, and calculations. The synthesis was done primarily at Columbia by Michael Inkpen, who was a post-doc in the Venkataraman group and is now an assistant professor at the University of Southern California. All the measurements were made by Woojung Lee, a graduate student in the Venkataraman group. The calculations were performed both by graduate students in the Venkataraman group and by collaborators from the University of Regensburg in Germany.

What’s next

The researchers are now exploring the practical applications of light-controlled single-molecule devices. This could include optimizing device performance, studying their behavior under different environmental conditions, and refining additional functionalities enabled by the metal-metal interface.

Reference: “Photooxidation driven formation of Fe-Au linked ferrocene-based single-molecule junctions” by Woojung Lee, Liang Li, María Camarasa-Gómez, Daniel Hernangómez-Pérez, Xavier Roy, Ferdinand Evers, Michael S. Inkpen and Latha Venkataraman, 16 February 2024, Nature Communications.
DOI: 10.1038/s41467-024-45707-z

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Hike, Forage, Read: Nature Ideas for Thanksgiving Week

Some ways to commune with nature this Thanksgiving week, whether outside or from a comfy chair. The post Hike, Forage, Read: Nature Ideas for Thanksgiving Week appeared first on Bay Nature.

Wild turkeys ( Meleagris gallopavo) in Ben Lomond, Calif., perform as role models for us all by going for a walk (and doing a passable Abbey Road cover impression while they are at it). runnerman19 via iNaturalist, CC-BY-NC Hardly anybody reads much news this week, according to our website analytics. Therefore, we shall save it for next week. Instead, here are some ways to commune with nature this Thanksgiving week, whether outside or from a comfy chair.   I. Go Outside It beats shopping. First: a roundup of stories in a roundup of stories? Yes. From 2021. Still good, ignore the pandemic references. The dinosaurs roam and flit among us. II. Eat (Very) Local We are not going to tell you to be grateful, but there is food all around us, if you are willing to learn how to find and process it. Two from Sara Calvosa Olson, a Karuk food writer who lives in the Bay Area: Bay nuts taste like hazelnuts with attitude and are not that hard to find. III. And Some Seasonally Appropriate Light Reading Various fowl stories from the archives. Every story from Bay Nature magazine is the product of a team dedicated to connecting our readers to the world around them and increasing environmental literacy. Please help us keep this unique regional magazine thriving, and support the ecosystem we’ve built around it, by subscribing today—you’ll get Bay Nature four times a year in your mailbox! Read This Next June 10, 2024 Baynature.org February 13, 2024 Magazine October 10, 2023 Magazine

Heart-shaped mollusc has windows that work like fibre optics

Tiny, solid windows in the shells of heart cockles let in light for the photosynthetic algae inside them – and they could show us how to make better fibre-optic cables

Heart cockles come in many colours and host photosynthetic algae inside their shellsDakota McCoy A heart-shaped mollusc has evolved tiny windows that work like fibre-optic cables, the first known example in nature. Heart cockles (Corculum cardissa) are bivalve molluscs a bit like clams that have a symbiotic relationship with photosynthetic algae that live inside them. The algae have a safe home, get light to photosynthesise and provide nutrients for their hosts. Unlike other bivalves, heart cockles don’t open their shells up wide, yet they somehow funnel light to their interior even while staying shut. Now, Dakota McCoy at the University of Chicago and her colleagues have found that there are transparent calcium carbonate crystal structures in the heart cockle shells that function like fibre-optic bundles, letting light inside to bathe the algae. “If you don’t have to open and can just have a transparent window, that’s a very safe way to irradiate your algae,” says McCoy. The researchers examined fragments of different heart cockle shells and the transparent structures within them, as well as the intensity and colour of light that gets through. They found that the windows were made from long, thin fibres of a mineral called aragonite – a form of calcium carbonate – which lets twice as much of the photosynthetically useful light through as it does harmful ultraviolet light. “We put on sunblock because UV causes mutations and cancer. The heart cockles are using these windows as a sunblock,” says McCoy. Heart cockle shells illuminated from within to show the transparent windows in their shells, which can be little triangles (left) or stripes (right)Dakota McCoy While the aragonite threads look similar to manufactured fibre optics, they lack a protective, insulating sheath, called cladding, yet transmit light just as effectively. This could serve as an inspiration for cladding-free fibre-optic cables, which would be cheaper to manufacture. The natural, UV-blocking properties of the shells could also be used to help protect corals, which, like the cockles, host photosynthetic algae inside them, but are more susceptible to environmental stresses like light and heat, says McCoy.

As Australia privatises nature repair, the cheapest approach won’t save our threatened species

Australia’s carbon credit scheme largely fails to protect threatened species, despite assumptions to the contrary. The findings provide cautionary lessons for the nature repair scheme.

ShutterstockAustralia is a world-leader in species extinction and environmental decline. So great is the problem, the federal government now wants to harness money from the private sector to pay for nature repair. Under the government’s new “nature repair market”, those who run projects to restore and protect the environment are rewarded with biodiversity credits. These credits can be sold to private buyers, such as corporations wanting to meet environmental goals. The nature repair market is similar in many ways to Ausralia’s existing carbon credit scheme. So, examining the extent to which carbon projects actually protect biodiversity is important as the government sets up the nature repair market. This was the focus of our new research. Alarmingly, we found Australia’s carbon credit scheme largely fails to protect threatened species, despite assumptions to the contrary. The findings provide cautionary lessons for the nature repair scheme. Spotlight on the carbon credit scheme Australia’s carbon credit scheme encourages activities that reduce carbon. They include planting trees, reducing animal grazing on vegetation, or retaining vegetation instead of cutting it down. Project proponents earn credits for carbon reduction, which can then be sold on a carbon market. The scheme also purports to offer “non-carbon” benefits. These include increasing biodiversity and expanding habitats for native species. Indeed, biodiversity conservation has underpinned the carbon credit scheme since it began in 2011. But does the carbon scheme actually benefit biodiversity? To answer this question, we overlaid the locations of carbon-reduction projects with the locations of habitat for threatened plants and animals species. We then scored the level of degradation of each habitat, and identified the processes imperilling the threatened species. So what did we find? Threatened species most in need of habitat restoration are the least likely to have their habitat restored under the carbon credit scheme. Projects under the scheme are primarily located in arid parts of Australia not suitable for growing crops – mostly vast cattle grazing leases. Carbon projects here involve inexpensive activities such as removing some cattle or managing weeds. These areas support habitat for only 6% of Australia’s threatened species. In other words, vegetation loss here generally doesn’t threaten species’ survival. In contrast, just 20% of carbon projects take place on productive agricultural land which supports nearly half of Australia’s threatened species. In these areas, property values are high and landholders can earn good money from farming. That means carbon-reduction projects are often less financially attractive than other land uses, so their number and size is limited. So what’s the upshot? Australia’s carbon projects are concentrated in areas containing little threatened species habitat, rather than where threatened species live and most need protecting. Government policies enable this perverse outcome, by giving preference to projects that can reduce carbon for the lowest cost. This has skewed projects towards unpopulated, relatively unproductive lands. There’s an upside It’s not all bad news, however. We found the carbon credit scheme may protect threatened species in some cases. Almost one-third (or 525) of Australia’s threatened species live in habitat that overlaps with projects under the scheme. In addition, five species whose habitat is not safeguarded in Australia’s protected areas, such as national parks, may also occur on land where carbon projects take place. A further 270 species with too-little protected habitat also overlap with the projects. The potential for positive benefits can be seen by looking at the two regions with the largest concentration of carbon projects in Australia. In the Murchison bioregion in Western Australia, a quarter of species rely on habitat that is not adequately protected elsewhere. In the Mulga bioregion in New South Wales and southwest Queensland, two-thirds of species rely on habitat inadequately protected elsewhere. The Mulga bioregion, one of two in Australia where the carbon credit scheme may protect threatened species. Shutterstock Lessons for nature repair Australia’s nature repair legislation came into effect in late 2023. It creates a framework for the nature repair market which is expected to launch early next year. Our findings provide important lessons for this market. Most importantly, they show a lowest-cost approach to generating credits is unlikely to benefit biodiversity. It will drive projects to marginal areas that do not overlap the ranges of species threatened by habitat loss. If nature repair investment is to prevent species extinctions, the Australian government must ensure taxpayer funds actually achieve these outcomes. The best way to do that is to speed up the progress of promised environmental law reform. Likewise, as global conservation increasingly looks to private finance and biodiversity markets, we must ensure funds are delivered to where they are most needed. Penny van Oosterzee is a Director of the Thiaki Rainforest Research Project, which generates Australian Carbon Credit Units as part of a restoration and research project in the Wet Tropics of Australia. Penny van Oosterzee has been a partner for two Australian Research Council projects. Jayden Engert receives funding from the Australian Commonwealth Government through an Australian Government Research Training Program Scholarship.

Negotiations Stall Over Some Crucial Issues on Final Day of UN Biodiversity Summit in Colombia

At the United Nations biodiversity summit in Colombia, negotiators struggle to find common ground on key issues, such as how to finance protections for 30% of the Earth's wild species by 2023 and how to make payments for nature’s genetic data

CALI, Colombia (AP) — At the United Nations biodiversity summit in Colombia, negotiators have struggled to find common ground on key issues.These include how to finance protections for 30% of the world's plants and animals by 2030, how to establish a permanent body for Indigenous peoples and how to make payments for nature’s genetic data that's used to create commercial products.The two-week conference, known as COP16, was due to wrap up Friday, although observers say negotiations could go into the weekend. In 2022, the biodiversity summit in Montreal, COP15, established a framework for countries to go about saving plummeting global ecosystems. This year’s follow-up summit was to put plans into motion. "COP15 was all about the ‘what’; this was supposed to be about the ‘how,’” Georgina Chandler, head of policy and campaigns at The Zoological Society of London, told The Associated Press. Wealthy nations pledged in Montreal’s summit to raise $20 billion in annual conservation financing for developing nations by 2025 — with that rising to $30 billion annually by 2030. “I don’t think we’ve seen governments come here with increased commitments towards the $20 billion significant enough that we’re going to achieve that," Chandler said. "That’s fallen a bit short.”The lack of financial pledges from wealthy countries prompted 20 ministers from the Global South to release a joint statement calling for the need to build trust among nations and for the Global North to meet its finance targets. In the run-up to negotiations, over 230 businesses and financial institutions demanded stronger policy ambitions to address the growing risks of nature loss, said Eva Zabey, CEO of Business for Nature. “In the final stretch at COP16, negotiations are stalling on crucial issues — including the mobilization of meaningful financial resources and a way for companies to ensure the benefits of nature are valued and shared fairly,” Zabey said. “We need governments to put aside their differences and demonstrate real and urgent leadership to deliver a strong COP16 outcome that incentivizes and drives necessary business action, further and faster, to halt and reverse nature loss by 2030,” she said. Who owns nature's DNA was a major topic at the summit. There was tension between poorer and developed countries over digital sequence information on genetic resources (DSI). This would oblige the sharing of benefits when genetic resources from animals, plants or microorganisms are used in biotechnologies. In Montreal, countries agreed to set up a global fund. “The DSI fund was scheduled to be adopted here two years ago. There is no clarity on how money will be gathered from companies,” said Oscar Soria, director of The Common Initiative. “As the text reads it is purely voluntary.” Sources told AP that there has been significant back and forth over wording in the draft agreement by nations. ’It’s clear that a number of points are going down to the wire in the COP16 negotiations," Catherine Weller, Director of Global Policy at charity Fauna & Flora said. One of the biggest controversies during talks was the blocking by a few countries of a Permanent Subsidiary Body for Indigenous Peoples and local communities, who Weller says bring valuable insights to many discussions. “We urge the negotiators to step up and ensure this is finalized,” she said.The Associated Press’ climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP’s standards for working with philanthropies, a list of supporters and funded coverage areas at AP.org.Copyright 2024 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.Photos You Should See - Sept. 2024

Green farming budget freeze 'will hit nature work'

Environmental groups warn that next year's farm payments budget will not be enough to protect nature.

Green farming budget freeze 'will hit nature work'Getty ImagesEnvironmental groups say more money needs to be invested in the annual farm payments budgetEnvironmental groups have warned that work to boost biodiversity across the UK countryside will be put at risk by the government’s decision to freeze the level of payments to farms in England.Farmers - already angry at changes to inheritance tax rules announced in the Budget - have been told payments from the public purse will be frozen next year.The Wildlife Trusts say the decision leaves a "monumental gap" between current environmental land management scheme (Elms) funding and what is needed to help farmers protect and boost wildlife and its habitats, while still producing food.The government said it would maintain the £2.4bn current level of farm payments in England for 2025/26, and that its commitment to farming was "steadfast".James GrindalJames Grindal says the government has failed to protect smaller family farmsOne farmer told the BBC he no longer believed the government understood the pressures of producing the nation’s food and protecting the countryside.James Grindal, a mixed arable and livestock farmer in Leicestershire, said: “I wouldn’t think the government has any idea."I think they ought to come and see the reality - the coalface of putting food on people’s plates."In Wednesday's Budget, the Chancellor announced that, while there would continue to be no inheritance tax due on combined business and agricultural assets worth less than £1m, above that there would be a 50% relief, at an effective rate of 20%, from April 2026.While some maintain the new policy is designed in part to cover large-scale landowners who may have invested in farmland for the tax benefit, many in farming say the £1m limit will hit small family farms hardest.Mr Grindal, who has two sons, aged 17 and 19, said he could be hit twice by the changes – on handing down the family farm, and if landowners sell off the land he rents.CLAVictoria Vyvyan from the CLA said the decision to freeze the farming budget would hit sustainable food production"I explained to my youngest son, who asked what the implications were, that if you take 20% off something every time someone dies, it’s not long before you get to nought," he said.“The Chancellor said she wants to protect small farms, but she is protecting the person who made a lot of money somewhere, bought a nice house with 20, 30, 50 acres to have a few horses on."Liberal Democrat environment spokesman Tim Farron said of the changes to agricultural property inheritance tax relief: "This is a family farm tax which risks ringing the death knell for local farmers and the small businesses who rely on them."Conservationists and environmental groups have spoken out on the government’s plans to maintain the farming payments budget at its current annual level of £2.4bn, the majority of which goes on environmental land management schemes.The Wildlife Trusts said around £3.1bn was needed for environmental farming schemes in England, and that maintaining the budget at current levels was a real-terms cut.'Largest ever budget'Elliot Chapman-Jones, the Trusts’ head of public affairs, said: “Ultimately, there is a monumental gap between current funding and what is needed to reverse wildlife declines, clean up rivers and significantly reduce the use of chemicals on farms."Tom Lancaster, land, food and farming analyst at the Energy and Climate Intelligence Unit think tank, said all the budget did was "maintain the status quo, just about keeping the show on the road for now".The Country Land and Business Association's (CLA) president Victoria Vyvyan said the decision to freeze the budget at the same level would hit hard-pressed farmers.She added: "It could hit sustainable food production and undermine improvements to wildlife habitats, flood management and access to nature."The government said the £2.4bn farming budget for England in 2025/26 would still be the “largest ever budget directed at sustainable food production and nature’s recovery”.Minister for Food Security and Rural Affairs Daniel Zeichner said: “Our commitment to farmers and the vital role they play to feed our nation remains steadfast.“That is why this government will commit to the largest ever budget directed at sustainable food production and nature’s recovery in our country’s history, enabling us to keep momentum on the path to a more resilient and sustainable farming sector.”

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