复活节岛上土壤中的一种
微生物产生的化学物质在亿万年的演变中，本应与人类没有直接关系。但奇迹的是，正因为它强有力的抗免疫特性，医生们得以成功地为一位小女孩进行肝移植
手术。
Figure 1: A plaque on Easter Island commemorating the discovery of a bacterium producing rapamycin, a potent immunosuppressant. Since its discovery, rapamycin has allowed the successful transplantation of organs into millions of patients (Image credit: Wikipedia)
图1：复活节岛上的铭牌，纪念一种能产生抗免疫物质——纳巴霉素的发现。自从发现它以来，纳巴霉素广泛应用于各种器官移植中。
In India, an excited young bride celebrates her upcoming wedding by coloring her hands bright yellow with turmeric, a spice that has been used for centuries as a key culinary ingredient. In France, a similar hallowed tradition demands a copious flow of red wine at weddings. In China, a bride and groom offer ginseng tea to their parents as part of a ritual.
在印度，一位喜笑颜开的新娘以一种独特的方式来庆祝她即将到来的大喜日——用姜黄将双手涂成淡黄色，这种东西千百年来都是作为厨房重要的材料。在法国，在婚礼上需要大量的红酒来举行一个类似的神圣传统。在中国，仪式的一个重要环节就是新郎新娘为自己父母献上人参茶。
Oblivious of all these events, thousands of miles away in the United States, scientists are struck by the remarkable effect that the active ingredients in turmeric, red wine and ginseng tea seem to have on a variety of disorders, from cancer to Alzheimer’s disease. Perhaps, they ardently hope, there’s a cure in there somewhere.
抛开这些事不说，在几千英里外的美国，科学家们被姜黄、红酒中活性物质的超凡作用给震惊了，而人参茶似乎对治疗从
癌症到
老年痴呆症的各种疾病都有效。
Chemistry is the human science. What the general public refers to as \"chemicals\" have a profound effect on our way of life. They can forge a bridge between the metabolism of a billion year-old sponge and the fervent hopes of a mother for her daughter’s life, between the joy of traditional weddings and food and that of seeing a loved one being cured of a terrible malady. Physics may concern itself with the beginnings of deep time and biology turns its eye on the origin of humanity itself. The wonders of physics and biology are undoubtedly spectacular, but chemistry is the science that most directly engages with our senses, the discipline that confronts us face-on every single day of our lives and demands that we react.
化学是人文科学。大家通常讲的“化学物品”对我们的日常生活影响巨大。它们能搭起一座座桥梁：不论是沉睡亿万年的细菌中的物质与一位渴望挽救她女儿生命的母亲，还是传统婚礼上的喜悦与见证自己被爱之人逃脱病魔。物理也许关注地球之初的样子，生物把注意力放在人类的起源。物理和生物无疑是绚丽夺目的，但化学却是一门和我们日常生活息息相关的科学，一门反映我们生活和需求的学科。
Chemicals delight, enrage, tease, beguile, provoke, subdue, reward, bully, soothe, punish, kill and save as directly and dramatically as human beings. Just like humans they have personalities that manifest themselves under the right circumstances. Like long-lost friends they can materialize in our lives in the form of a life-saving drug, a dab of color on a dull day or the material in a particularly comfortable new mattress. And like sworn enemies they can incapacitate us on battlefields, deform our children and provoke us to endless debate and politicking about the effects of their vanishingly small traces in the environment. Chemistry is the middle kingdom, the land which engages us with its familiarity at all levels, from the trite to the life altering. Like the landscape of Middle Earth, it is full of fascinating and baffling curiosities, triumphs and tragedies, foolishness and wisdom.
化学和人类一样有喜怒哀乐爱恨情仇。和人类一样，在特定的环境下它们会表现出它们特定的特点。像多年不见的朋友，它们会化身成救命良药，或者是无聊一天中的绚丽色彩，或者是一席舒适的枕头。也可像誓死不从的敌人，它们可以在战场上击败我们，使我们的小孩变形，激起我们对于它们对环境影响的永无止境的争论。
As we celebrate the International Year of Chemistry this year, it is worth pondering the nature of this \"central science\" [1]. What makes chemistry unique is that its defining constituents- molecules- can have a startlingly direct relationship on an individual basis with world events and the rise and fall of nations. No other science can claim such well-defined and powerful connections between a handful of its building blocks and key aspects of history, economics culture. Consider just two facts. Even today, the strength of the economy of a country can be judged by the magnitude of its production of a single chemical- sulfuric acid [2].
借着今年国际化学年的声势，细细琢磨这门“核心科学”的本质是值得的。使化学鹤立鸡群的是它那些特定的分子能与一个国家的兴衰荣辱有直接的关联。再也没有哪门科学能将那些建筑材料和历史人文经济紧密的联系在一起。就考虑两个事实：即使今天，硫酸的产量仍可作为衡量一个国家的经济水平高低的标准。
Or consider that it was cellulose- in the form of cotton- that was at the root of slavery and the American Civil War. During the early days of imperialism, it was avarice for a select few materials like indigo dyes and silk that led expansion and trade in the East [3]. And wars have been fought over substances like saltpeter in South America [4] and opium in China [5] whose properties and allure were defined by one or two dominant molecules; sodium nitrate in the case of saltpeter and morphine in the case of opium. It is not an exaggeration to say that individual molecules have held remarkable sway over entire economies, cultures and political relationships. Throughout history, chemistry through its forging of precious and unique arrangements of atoms has influenced the fortunes of humans in visceral and vivid ways.
在看看以棉花形式出现的纤维，它可是奴隶制的根源和美国内战的起因。在帝国主义初期，就是因为对于靛类染料和丝绸的无限渴望才助长了远东地区的贸易昌盛。很多战事都是为了一些物质而拉开，例如南美洲的硝石和中国的鸦片，这些国家的所有财力和物力都被一种或两种分子控制着：如硝石中的硝酸钠和鸦片中的吗啡。如此说来，分子控制一个国家的政治经济文化毫不为过。纵观古今，化学以各种原子精妙而独特的组合结构，影响着人类命运的沉与浮。
Figure 2: A battle scene from the Opium Wars from the mid-nineteenth century. Opium which is extracted from the seeds of the poppy plant owes its properties to one dominant molecule- morphine. (Image)
图2：19世纪中期鸦片战争中的一场海战。从罂粟花中提取出来的鸦片主要是靠一种物质发挥功效——吗啡。
It is precisely because chemistry is the human science that people have a decidedly ambivalent and often confused relationship with it. You won’t hear many heated debates on television about the fine tuning of the cosmological constant or the evolution of the opposable thumb, but the media is rife with vociferous controversies about the side effects of drugs against heart disease, the apparent proliferation of bisphenol A in the environment [6] or the rise of ‘designer’ narcotics that provide ‘legal highs’ [7]. Every one of these controversies centers directly on a molecule or a family of molecules, and each one affects millions of people personally every day.
确切地说，那是因为人们对于化学这门人文科学既爱又恨。关于宇宙常抑或可相对拇指的高谈阔论，你在电视上可能很少听到，但是媒体们却对各种药物（例如心脏病药物、影响环境的双酚A、日益猖獗的合法精神类麻醉药物）的副作用颇为津津乐道。这些争论的焦点都汇聚于一种或一类分子上，每天它们都影响着数以万计的人。
This direct connection to all our problems and promises is what makes chemistry stand out and elevates it from its reductionist roots in physics. Molecules are more than the sum of their constituent atoms, and they connect with our senses in ways that are much more tangible and diverse than abstract notions of energy, forces and fields.
正是这种与我们日常生活有着千丝万缕的联系才使得化学从物理中脱颖而出。分子不仅仅是一堆原子的集合，相比能量、力和场等抽象概念，它们以一种更加实体化更加多样化的形式出现在我们面前。
When I smell freshly cut grass, I am directly smelling a simple molecule called cis-3-hexenol; when I first smelt this compound and then smelt cut grass, it etched an unforgettable connection in my mind. Gravity may be all encompassing, but you can’t gift a small piece of gravity to someone on his or her birthday in a box, which they can then spray on their clothing. Quarks may be the ubiquitous building blocks of matter, but a quark does not allow you to readily distinguish between two compounds with exactly the same chemical formula, one of which can cure your diabetes while the other kills you by paralyzing your nerves.
当我闻到刚割下的嫩草时，我首先闻到的是一种叫做己烯醇的分子；当我第一次闻到这种化合物，再闻那些割下的嫩草，我的脑子中就会留下不可磨灭的印象。重力无处不在，但是你不可能在某人的生日宴会上送给他一盒重力，然后它们自动扑到他们身上吧。夸克也许是世间万物的基石，但一个夸克分子不会使你轻而易举地就分辨出有相同化学分子式的两种化合物，一种能治愈你的
糖尿病，而另一种却能使你神经瘫痪而死。
Such diversity cannot be captured by physics alone. And for all the profound implications of the second law of thermodynamics for life, liberty and the pursuit of happiness, it’s hard to have a personal relationship with entropy. It’s equally hard to fathom the ages of geological time that drive evolution or to directly see the folding and unfolding of DNA on an everyday basis. But to experience the very soul of chemistry, the actual molecules without which the science would not exist, one only has to reach out into his or her medicine closet, kitchen, insecticide drawer and laundry room. In each one of these places you will find a microcosm of molecules which directly impact the look, smell, touch, and sound of everything that you see.
诸如此类的多样化不可能单靠物理的一己之力。当你在日常生活、自由和追寻幸福中，你很难和大名鼎鼎的热力学第二定律扯上关系。同样，在日常生活中，你是无法看透这个逐渐演化的地质年代或者是DNA的盘旋曲折。但是为了领悟到化学的真谛——无分子不科学，你只需随处到医药箱、厨房、杀虫剂的柜子或洗衣房走走看看即可。在每一个这样的地方，你都可以发现分子的微观世界，它们会直接影响你所见物质的外观、气味、触感和声音。
It is this very personal impact of molecular structures on our senses and sensibilities that has created the perceived and real fear of everything \"chemical\". This fear often causes confusion, leading us to brand anything \"natural\" (supposedly including snake venom) as good and anything \"artificial\" (supposedly including a synthetic drug for heart disease) as bad. It has caused the lexicon of chemistry to collide with popular culture in ways that leave chemists perplexed; the word \"organic\" for instance, especially as connected to the organic food movement, has completely transcended its original meaning in the chemist’s dictionary. For a chemist, many organic compounds like dioxin and botulism toxin are extremely toxic, while inorganic compounds like sodium chloride or lithium are harmless or even beneficial.
正是由于化学分子结构对于我们各感官的影响才使得我们害怕所有以“化学”开头的物质。这些恐惧经常引起混乱，导致我们天真地以为凡是自然的(包括蛇毒液)都是好的，凡是人造的（包括治疗心脏病的合成药物）都是坏的。那些令化学家们困惑的主流文化和化学的定义相抵触。例如，“有机”一词，特别是和有机食品运动联系在一起时，完全胜过了其在化学家心目中的地位。从一位化学家角度来看，许多有机化合物如二恶英和肉毒毒素都是有毒物质，而像氯化钠和锂等无机化合物则是无害甚至有益的。
The fear of chemicals is often unjustified but its roots reach out into the very nature of chemical substances and indeed into human nature itself. There is a deep-seated reason why the tale of Jekyll and Hyde has transcended cultures and ages. It is because we understand that there is a Jekyll and Hyde in each one of us, waiting for the right moment to step out of the shadows. This ambiguity in human behavior translates faithfully to chemical behavior; like Jekyll and Hyde, almost every arrangement of atoms inherently presents two faces to us and this has led us to sustain a love-hate relationship with chemicals.
对化学的恐惧是毫无根据的，但却深埋在各种化学物质和我们人类本性中。 杰柯尔与海德（化身博士）的故事能够盛传至今是有一个很深层次的原因。那是因为我们明白每个人心中都有一个杰柯尔与海德伺机而行。这种人类的双面性行为和化学如出一辙。就像杰柯尔与海德，几乎所有原子都会显示出两种面貌，从而导致我们对化学既爱又恨。
But it is up to us to decide which face we want to see. Do we want to see the murderous face of nitrogen mustard gases which were used in World War 1 during the first large-scale waging of chemical warfare? Or do we want to see the noble face of nitrogen mustard analogs which peace-loving men and women harnessed a few decades later into the first anticancer drugs [8]?
但选择权在我们手中。我们是希望看到氮芥毒气在一战时期作为大规模化学武器横行肆虐呢？还是希望看到希望它数十年后被和平之士制作成抗癌药物。
Some of the most beneficial compounds in anticancer therapy owe their origin to some of the most gruesome agents used in war. The adage \"what does not kill you makes you stronger\" applies more to chemistry that we can imagine. Phosphate fertilizers pose another example of a chemical Jekyll and Hyde; these compounds which have saved literally billions from starvation are also responsible for algal blooms in streams and rivers which can kill off entire ecosystems by choking their nutrient and oxygen supply.
在抗癌治疗上，一些极其有用的化合物最初都是用于战争中的恐惧杀手。古云“任何不能把你击倒的障碍，只能把你变得更坚强”之理深藏于化学之中。磷酸盐肥料就是化学上的“杰柯尔与海德的一个例子。这些化合物对于拯救饥饿确实功不可没，但同时对于湖泊河流的海藻污染又有不可推卸的责任，这些得以滋生海藻独霸营养和氧气，戕杀了整个生态系统。
Sometimes it takes a simple change in the orientation of certain atoms to transform a cure into a monster. Thalidomide infamously caused birth defects when it was administered to pregnant women as a pill for morning sickness. In this case the culprit was not a different molecule but simply the mirror image counterpart of the compound (created by metabolism inside the body) that caused such grievous harm.
有时候一些特定原子的细微变化可以导致良药变成毒药。镇定剂用于治疗孕妇晨吐的同时也会导致胎儿先天畸形，这都拜这个分子的镜像化合物所赐。
Alice herself could not have imagined the nightmare waiting for her on the other side of the looking glass. But ironically, thalidomide has recently seen resurgence on a limited scale as a therapy for multiple myeloma, a deadly disease. Like some human beings, molecules can be forgiven and resurrected for useful purposes after being cast aside as pariahs. We all deserve a second chance.
Alice根本不能想象镜子另一边等待着她的噩梦（此句着实不懂其意，请高人指教）但有意思的是，最近镇定剂在一种致命疾病——多发性骨髓瘤的治疗上初现成效。就像人类一样，分子只要悔过自新也可重新做人。我们都有回头是岸的机会。
Figure 3: The tale of Jekyll and Hyde- dramatized here in a movie poster- serves as an accurate metaphor for molecules, many of which can demonstrate strikingly different properties depending on subtle changes in shape, concentration or arrangement of atoms. (Image)
图3：杰柯尔与海德（化身博士）的故事（见电影海报上）是分子的最好隐喻。在原子形状、浓度或组合上失之毫厘的改变，将会显现出截然不同的特性。
We may not have witnessed this proliferation of beneficial and harmful qualities from such a multitude of molecules had it not been for the one property of chemistry that makes it a unique science. Chemistry is the sole human activity which can truly create that which never existed before in stunningly diverse quality and quantity [1].
也许我们不曾目睹过这些分子所带来的利与弊。化学是一门唯一可以创造出质与量多样性的科学。
In the last one hundred years or so, chemists and especially organic chemists have transformed the science of creating molecules to the level of a finely honed art. Making molecules of arbitrary complexity on demand is an ability that reinforces humans’ position as the dominant species on our planet as much as any other. It exemplifies the highest forms of creativity of the kind signified by Shakespeare, Beethoven, Michelangelo and Newton. It is not an exaggeration to say that from a conceptual standpoint, chemical synthesis has been a world-shattering paradigm underpinning all of modern civilization, equal in importance to the invention of the calculus and the discovery of electricity.
过去100年至今，化学家尤其是有机化学家把创造分子转变成一项精细的艺术。根据需求来创造出分子是一种能力，一种能证明人类在此星球上占绝对统治地位的能力，正如同莎士比亚、贝多芬、米开朗琪罗和牛顿等人至高无上的创造力一样。毫不夸张地从理论上讲，化学合成是当今文明的顶梁柱，其重要性丝毫不亚于微积分的发明和电的发现。
Synthetic chemical substances so fully permeate our environment that it is all too easy to forget that someone had to discover them. Everything from the chair that we sit in to the clothes that we wear to the food that we eat to the drugs that we are prescribed to the buildings that we inhabit to the modes of transportation that get us to work consist in large part of synthetic molecules that did not exist before in nature. The ability of chemists to design and make these molecules is almost fearsome in its efficiency and versatility. Part of the fear of chemicals stems from the sheer novelty of new chemical substances and their all-pervasive presence in our lives. Sometimes we tend to fear the most, that which is most familiar.
合成的化学物质充满我们生活的每个角落，以至于我们太习以为常，忘记了发明它的人。我们平时做的椅子、穿的衣服、吃的药物、住的楼房、开的汽车，很大一部分都是由原本自然界不存在的合成分子组成。化学家们设计创造出分子的能力在其使用效率和多功能用途上让人不寒而栗。对于化学物质的恐惧一部分是源于对这些新化学物质的好奇和他们对于日常生活的无孔不入。有时，我们最害怕的往往是我们最熟悉的。
Figure 4: This sequence of steps illustrates the complex series of reactions- involving dozens of reagents and intermediate compounds- typically required for synthesizing a useful molecule. In this case the molecule is merrilactone A, a compound isolated from the Chinese star anise spice which may have have therapeutic value against neurodegenerative diseases. (Image credit: Wikipedia)
图4：这一系列化学反应揭示了反应的复杂度——包含许多反应物和中间物，最终才能制成有用的合成分子。图中的分子是merrilactone A，一种从中国大茴香中提取出来的化合物，在神经病变疾病中有药用价值。
One thing is for sure; whether we love or despise these chemicals, we cannot imagine a life without them. Much is made sometimes of the evils of the chemical and pharmaceutical industries, but there cannot be a soul who would deny the untold number of lives saved by antibiotics and antiviral drugs largely developed by the pharmaceutical industry. Oil companies may be everyone’s favorite villains, but it is prudent to consider the tremendous net impact which the refining of crude oil by chemical means has had on transportation and power generation in the twentieth century. \"Plastic is fantastic\", not only in the popular song but in all aspects of real life, from surgical sutures to the powdery material used in diapers.
有一事是值得肯定地，无论我们对于这些化学物质是爱是很，我们的生活都离不开它们。很多舆论认为有时候制药厂和化学是邪恶的，但没人敢否定制药厂制造的抗生素和抗病毒药物拯救了无数条生命。
The organic food movement eschews the use of artificial fertilizers, yet we can never forget a simple fact; nitrogen fertilizers were made possible by the Haber-Bosch process, a method literally of turning air into bread, which by some estimates kept a fifth of the world’s population alive [4]. Whatever our feelings are about the humans who have created these molecules, the life-saving properties of the molecules themselves stand proudly in splendid isolation. More than any other science chemistry has directly fed us, clothed us and kept us from dying. It has overwhelmingly contributed to the high standard of living which we aspire to and take for granted.
有机食品运动回避掉了有机化肥的好处，但我们不能忘记一个简单的事实：氮类化肥是从哈伯-博施法（合成氨）而来，这是一种方法正如同把空气变成面包一样，养活了世界五分之一的人口。无论我们对创造了这些分子的人吃何种成见，这些救人性命的分子仍可傲然于世。比起其它科学，化学供我们吃穿，为我们关闭死亡之门。它赐予我们高质量的生活水平，而我们只是理所当然地享用着。
一个没有化学的世界将会是地狱，人类无法保护自己免遭自然的戕害，会因缺乏燃料而无法长途旅，会在微生物面前束手就擒，会因小小的伤口而丧命，会因饥荒而饿死。简单地说，一个没有化学的世界将会是一个连最极端的环保主义者和无用药主义者都不想生存的世界。
As we advance into the twenty-first century, this most human of all sciences will continue to amaze and thwart us with its complexity, utility and ambiguity. Chemistry will continue to be at the center of our efforts to solve the energy crisis, develop personalized drugs and transform agriculture. There will no doubt be tension between humans and the molecules they create. Under such circumstances public education will go a long way in dispelling unrealistic fears about molecules and their impact on human health and the environment, and this is one goal which the International Year of Chemistry is vigorously trying to promote. While these practical problems are being solved, chemists will continue to quietly enjoy what they have enjoyed doing for hundreds of years. They will gaze at colorful crystals, unravel the structures of alkaloids from frog skin, simulate the complex motion of enzymes on computers and study the cellular reactions that fuel life.
当我们进入21世纪时，这个可叹、可爱而又可恨的人文学科将会继续伴我们前行。化学将是我们解决能源危机的关键，为我们发展药物以及农业。毫无疑问人类及其创造出来的分子也会有一段紧张的关系。在此种环境下，公共教育在打消人们那些不切合实际的恐惧和分子在健康与环境上仍有很长一段路要走，这也是今年国际化学年努力的方向之一。在这些实际问题得以解决的同时，化学家们会静静享受着百年来他们一直热衷做的事情。他们注视着五彩缤纷的结晶，试图揭开青蛙皮肤上生物碱的结构，在电脑上模拟酶的产生，探索维持生命的细胞反应。
Ultimately the truth about this human science goes deeper. We need to realize that the power of molecules to shock and awe resides in their creators. The physicist Richard Feynman once quoted an old Japanese proverb: \"To every man is given the key to heaven. The same key opens the gates of hell\". Interestingly, the dominant model for the mechanism by which a small molecule like a drug fits into the active site of a disease-promoting enzyme and modulates its activity is that of a \"lock and key\". Many drugs act by being the ideal key in a particular lock, but they can also fit into other unwanted locks and cause toxic side effects; the same key that cures a disease may open the gates of hell by causing overwhelming side effects. Chemists who design drugs keep on trying to make the key fit only one lock.
最终这门人文科学越走越远。须知分子的能力全拜它们的创造者所赐。物理学家Richard Feynman曾引用过一句古老的日本谚语：“人人生而平等，拥有一把可以打开天堂和地狱大门的钥匙。许多药物是一把特别锁的钥匙，但他们同时也能打开其它无用的锁，导致致命的副作用；治疗一种疾病的钥匙也许能打开通往地狱的大门，因为它会产生不可估计的副作用。设计药物的化学家就必须不停地确保这些钥匙只能开一把锁。
The metaphor extends to all of chemistry. Every chemical substance is a key to the gates of heaven and hell. Ultimately we are the ones who decide what gate it will open. We hope to choose wisely.
这个隐喻扩展到化学的所有领域。每一种化学物质都是一把开启天堂和地狱的钥匙。最终决定哪扇门被打开的人是我们。希望我们做出明智的选择。
作者：
2011-8-20